Method for obtaining quantity of resource elements in communication process and related apparatus

ABSTRACT

A method for obtaining a quantity of resource elements in a communication process, comprising: determines a downlink control information format of downlink control information, obtains, based on the downlink control information format, a quantity of resource elements occupied by a demodulation reference signal (DMRS); and determines a size of transport block (TBS) based on the quantity of resource elements occupied by the DMRS.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of International ApplicationPCT/CN2019/074997, filed on Feb. 13, 2019, which claims priority toChinese Patent Application No. 201810150365.0, filed on Feb. 13, 2018,all of the aforementioned patent applications are hereby incorporated byreference in their entireties.

TECHNICAL FIELD

This application relates to the communications field, and morespecifically, to a method for obtaining a quantity of resource elementsin a communication process and a related apparatus.

BACKGROUND

When a base station performs data communication with user equipment(user equipment, UE), the base station may schedule data for the UE. Forexample, the base station may allocate a time domain resource and afrequency domain resource to the UE via signaling. The time domainresource and the frequency domain resource may be collectively referredto as a time-frequency resource.

When scheduling data for the UE, in addition to allocating atime-frequency resource, the base station further needs to determine asize of a data block transmitted on the time-frequency resource. Thesize of the data block may also be referred to as a size of transportblock (transmission block size, TBS). The TBS indicates a size of bitinformation carried on a time-frequency resource scheduled by the basestation.

Usually, to determine a TBS, a quantity of REs occupied by ademodulation reference signal (demodulation reference signal, DMRS)needs to be determined first. Therefore, how to determine the quantityof REs occupied by the DMRS is a technical problem to be resolved.

SUMMARY

This application provides a method for obtaining a quantity of resourceelements in a communication process and a related apparatus, so that aquantity of REs occupied by a demodulation reference signal can bedetermined. This helps determine a TBS, and further helps ensurecommunication reliability.

According to a first aspect, this application provides a method forobtaining a quantity of resource elements in a communication process.The method includes: obtaining first information, where the firstinformation includes at least one type of the following information: adownlink control information format, a configuration type of ademodulation reference signal, a quantity of symbols occupied by thedemodulation reference signal, a waveform, a radio network temporaryidentifier scrambling manner of downlink control information, a datachannel type, a quantity of symbols occupied by a data block, and aposition of a symbol occupied by the data block; and obtaining, based onthe first information, a quantity, corresponding to the firstinformation, of resource elements occupied by the demodulation referencesignal, where there is a correspondence between the first informationand the quantity of resource elements occupied by the demodulationreference signal.

In the method, a communications apparatus may directly obtain thequantity of resource elements occupied by the demodulation referencesignal, based on the correspondence between the first information andthe quantity of resource elements occupied by the demodulation referencesignal. This helps determine a TBS, and further helps ensurecommunication reliability.

In a possible implementation, the first information is in a one-to-onecorrespondence with the quantity of resource elements occupied by thedemodulation reference signal.

In this implementation, the communications apparatus can obtain, basedon the correspondence by obtaining only the first information, thequantity of resource elements occupied by the demodulation referencesignal.

In a possible implementation, when the first information includes thedownlink control information format, the obtaining, based on the firstinformation, a quantity of resource elements occupied by thedemodulation reference signal includes: if the downlink controlinformation format is downlink control information format 1_0, obtainingthat the quantity of resource elements occupied by the demodulationreference signal is 4 or 6; and/or if the downlink control informationformat is downlink control information format 0_0, obtaining that thequantity of resource elements occupied by the demodulation referencesignal is 6 or 4.

In a possible implementation, when the first information includes theconfiguration type of the demodulation reference signal, the obtaining,based on the first information, a quantity of resource elements occupiedby the demodulation reference signal includes: if the configuration typeof the demodulation reference signal is configuration type 1, obtainingthat the quantity of resource elements occupied by the demodulationreference signal is 6; and/or if the configuration type of thedemodulation reference signal is configuration type 2, obtaining thatthe quantity of resource elements occupied by the demodulation referencesignal is 4.

In a possible implementation, when the first information includes theconfiguration type of the demodulation reference signal and the quantityof symbols occupied by the demodulation reference signal, the obtaining,based on the first information, a quantity of resource elements occupiedby the demodulation reference signal includes: if the configuration typeof the demodulation reference signal is configuration type 1, and thequantity of symbols occupied by the demodulation reference signal is 1,obtaining that the quantity of resource elements occupied by thedemodulation reference signal is 6; and/or if the configuration type ofthe demodulation reference signal is configuration type 1, and thequantity of symbols occupied by the demodulation reference signal is 2,obtaining that the quantity of resource elements occupied by thedemodulation reference signal is 12; and/or if the configuration type ofthe demodulation reference signal is configuration type 2, and thequantity of symbols occupied by the demodulation reference signal is 1,obtaining that the quantity of resource elements occupied by thedemodulation reference signal is 4; and/or if the configuration type ofthe demodulation reference signal is configuration type 2, and thequantity of symbols occupied by the demodulation reference signal is 2,obtaining that the quantity of resource elements occupied by thedemodulation reference signal is 8.

In a possible implementation, the obtaining, based on the firstinformation, a quantity of resource elements occupied by thedemodulation reference signal includes: obtaining the quantity ofresource elements occupied by the demodulation reference signal, basedon the correspondence between the first information and the quantity ofresource elements occupied by the demodulation reference signal.

In a possible implementation, the method is performed by a terminaldevice, and the correspondence in the method is configured by theterminal device according to a communication protocol or received by theterminal device from an access network device.

According to a second aspect, this application provides a communicationsapparatus. The communications apparatus includes a module configured toperform the method in any one of the first aspect or the possibleimplementations of the first aspect. The module included in thecommunications apparatus may be implemented by using software and/orhardware.

According to a third aspect, this application provides a communicationsdevice. The communications device includes at least one processor and acommunications interface. The communications interface is used by thecommunications device to exchange information with anothercommunications device, and when a one or more instructions is executedby the at least one processor, the method in any one of the first aspector the possible implementations of the first aspect is performed.

Optionally, the communications device may further include a memory. Thememory is configured to store a program and data.

Optionally, the communications device may be an access network device,for example, a base station, or may be a terminal device.

According to a fourth aspect, this application provides a computerreadable storage medium. The computer readable storage medium storesprogram code executed by a communications device. The program codeincludes an instruction used to perform the method in any one of thefirst aspect or the possible implementations of the first aspect.

For example, the computer readable storage medium may store program codeexecuted by an access network device (for example, a base station) or aterminal device, and the program code includes an instruction used toperform the method in any one of the first aspect or the possibleimplementations of the first aspect.

According to a fifth aspect, this application provides a computerprogram product including an instruction. When the computer programproduct runs on a communications device, the communications deviceexecutes an instruction for the method in any one of the first aspect orthe possible implementations of the first aspect.

For example, when the computer program product runs on an access networkdevice (for example, a base station) or a terminal device, the accessnetwork device or the terminal device executes the instruction for themethod in any one of the first aspect or the possible implementations ofthe first aspect.

According to a sixth aspect, this application provides a system chip.The system chip includes an input/output interface and at least oneprocessor, and the at least one processor is configured to invoke aninstruction in a memory to perform an operation of the method in any oneof the first aspect or the possible implementations of the first aspect.

Optionally, the system chip may further include at least one memory anda bus, and the at least one memory is configured to store theinstruction executed by the processor.

According to a seventh aspect, this application provides acommunications system. The communications system includes thecommunications device in the third aspect.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic structural diagram of a communications system towhich a communication method according to an embodiment of thisapplication may be applied;

FIG. 2 is a schematic diagram of a DMRS pattern according to anembodiment of this application;

FIG. 3 is a schematic diagram of a DMRS pattern according to anotherembodiment of this application;

FIG. 4 is a schematic diagram of a DMRS pattern according to anotherembodiment of this application;

FIG. 5 is a schematic diagram of a DMRS pattern according to anotherembodiment of this application;

FIG. 6 is a schematic flowchart of a communication method according toan embodiment of this application;

FIG. 7 is a schematic structural diagram of a communications apparatusaccording to an embodiment of this application;

FIG. 8 is a schematic structural diagram of a communications deviceaccording to an embodiment of this application;

FIG. 9 is a schematic structural diagram of a system chip according toan embodiment of this application; and

FIG. 10 is a schematic structural diagram of a communications systemaccording to an embodiment of this application.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

With reference to the accompanying drawings, the following describes thetechnical solutions in this application by using an example in whichcommunications apparatuses are a terminal device and a base station.

FIG. 1 is a schematic structural diagram of a communications system towhich a communication method according to an embodiment of thisapplication may be applied. It should be understood that this embodimentof this application is not limited to a system architecture shown inFIG. 1. In addition, an apparatus in FIG. 1 may be hardware,functionally divided software, or a combination thereof.

It may be obtained from FIG. 1 that the communications system to whichthe communication method in this embodiment of this application may beapplied may include a base station 110 and UE 120.

It should be understood that a specific type of the base station 110 isnot limited in this embodiment of this application. In systems usingdifferent radio access technologies, devices having a base stationfunction may have different names. For ease of description, in all theembodiments of this application, the foregoing apparatuses that providea wireless communication function for a terminal are collectivelyreferred to as a base station, for example, a base station device in afurther network or a picocell base station device (pico).

The base station 110 includes but is not limited to: an evolved NodeB(eNB), a radio network controller (RNC), a NodeB (Node B, NB), a basestation controller (BSC), a base transceiver station (BTS), a home basestation (for example, a home evolved NodeB or a home Node B, HNB), abaseband unit (BBU), an access point (AP) in a wireless fidelity (Wi-Fi)system, a wireless relay node, a wireless backhaul node, a transmissionpoint (transmission and reception point, TRP; or TP), or the like; ormay be a gNB or a transmission point (TRP or TP) in a 5G system such asan NR system, one antenna panel or one group of antenna panels(including a plurality of antenna panels) of a base station in a 5Gsystem; or may be a network node forming a gNB or a transmission point,such as a baseband unit (BBU) or a distributed unit (DU).

The UE 120 may communicate with one or more core networks via a radioaccess network (RAN). The UE may also be referred to as an accessterminal, a terminal device, a subscriber unit, a subscriber station, amobile station, a mobile console, a remote station, a remote terminal, amobile device, a user terminal, a wireless communications device, a useragent, or a user apparatus. The UE may be a cellular phone, a cordlessphone, a session initiation protocol (SIP) phone, a wireless local loop(WLL) station, a personal digital assistant (PDA), a handheld devicehaving a wireless communication function, a computing device, anotherdevice connected to a wireless modem, an in-vehicle device, a wearabledevice, a terminal device in the Internet of things or internet ofvehicles, a terminal device in any form in a future network, or thelike.

When the base station no performs data communication with the UE 120,the base station no may schedule data for the UE 120. For example, thebase station no may allocate a time domain resource and a frequencydomain resource to the UE 120 via signaling. The time domain resourceand the frequency domain resource may be collectively referred to as atime-frequency resource.

When scheduling data for the UE 120, in addition to allocating atime-frequency resource, the base station no needs to determine a TBS onthe time-frequency resource.

The TBS may be calculated based on a quantity of resource elements (RE),used to transmit a data block, on a time-frequency resource scheduled bythe base station.

For example, when performing scheduling for the UE in a form of slots,the base station may calculate a TBS based on a quantity of REs, used totransmit a data block, in one resource block (RB) in one slot. Foranother example, the quantity of REs may be multiplied by a modulationscheme, and then an obtained result is multiplied by a bit rate and aquantity of layers to obtain the TBS.

A quantity of REs, used to transmit a data block, in one RB in one slotmay be calculated by using a total quantity of REs that are allocatedfrom one RB in the slot to transmit data, a quantity of REs, occupied bya demodulation reference signal, in these REs, and a quantity of otherREs, unable to be used to transmit a data channel, in these REs. Datacannot be mapped to the REs unable to be used to transmit a datachannel. For example, an RE occupied by a channel stateinformation-reference signal (CSI-RS) cannot be used to transmit a datachannel.

In other words, to determine a TBS, a quantity of REs used to transmit adata block needs to be determined first; and to determine the quantityof REs used to transmit a data block, a quantity of REs occupied by ademodulation reference signal needs to be determined first.

The demodulation reference signal in this application may include a datademodulation reference signal and/or a phase tracking reference signal(PTRS). The data demodulation reference signal (DMRS) may be a referencesignal used for data demodulation, or may be a reference signal used fordata channel estimation. The PTRS may be a reference signal used forphase tracking and/or phase estimation.

When downlink data block transmission is performed between the basestation 110 and the UE 120, on a base station side, the base station nomay send, to the UE 120, a demodulation reference signal and downlinkcontrol information (DCI) used to schedule downlink data transmission,determine a quantity of REs, occupied by the demodulation referencesignal, in a resource scheduled by the DCI, calculate a TBS based on thequantity, and send the data block to the UE 120 based on the TBS; and ona terminal side, the UE 120 may receive the DCI and the demodulationreference signal, determine a quantity of REs, occupied by thedemodulation reference signal, in a resource scheduled by the DCI,calculate a TBS based on the quantity, and receive, based on the TBS,the data block sent by the base station 110.

When an uplink data block is transmitted between the base station 110and the UE 120, on a base station side, the base station 110 may send,to the UE, DCI used to schedule uplink data transmission; on a terminalside, the UE 120 may send a demodulation reference signal to the basestation 110, determine a quantity of REs, occupied by the demodulationreference signal, in a resource scheduled by the DCI, calculate a TBSbased on the quantity, and send the uplink data block to the basestation no based on the TBS; on the base station side, the base stationno receives the demodulation reference signal, determines a quantity ofREs, occupied by the demodulation reference signal, in a resourcescheduled by the DCI, calculates a TBS based on the quantity, andreceives, based on the TBS, the uplink data block sent by the UE 120.

It should be understood that, in this embodiment of this application,the quantity of REs occupied by the demodulation reference signal may bea quantity of possible REs, used to transmit the demodulation referencesignal, in the resource scheduled by the DCI. In other words, in thisembodiment of this application, the quantity of REs occupied by thedemodulation reference signal may be greater than or equal to a quantityof REs, actually used to transmit the demodulation reference signal, inthe resource scheduled by the DCI.

For example, the resource scheduled by the DCI may include 12 REs thatmay be used to transmit the demodulation reference signal, where only 8REs in the resource may be actually used to transmit the demodulationreference signal. In this embodiment of this application, the quantityof REs occupied by the demodulation reference signal may be 12.

The DCI is information used for data scheduling or signal transmission,and may be referred to as control information for short. Data schedulingincludes uplink data scheduling and/or downlink data scheduling. Signaltransmission includes signal sending and/or receiving. The DCI may betransmitted via higher layer signaling, or may be transmitted viaphysical layer signaling. This is not limited in this application.

The higher layer signaling may be radio resource control (RRC)signaling, medium access control (MAC) signaling, or other higher layersignaling.

The technical solutions proposed in this application mainly includemethods used by the base station 110 and the user equipment 120 todetermine the quantity of REs, occupied by the demodulation referencesignal, in the resource scheduled by the DCI.

In the method in this embodiment of this application, a correspondencemay be predefined between the quantity of REs occupied by thedemodulation reference signal and at least one type of the followinginformation: a DCI format, a configuration type of the demodulationreference signal, a quantity of symbols occupied by the demodulationreference signal, a position of a symbol occupied by the demodulationreference signal, a waveform, a radio network temporary identifier(RNTI) scrambling manner of DCI, a data channel type, a quantity ofsymbols occupied by a data block, and a position of a symbol occupied bythe data block, and then the correspondence is configured on the basestation 110 and the UE 120. In this way, after obtaining the at leastone type of information, the base station 110 and the UE 120 may obtain,based on the at least one type of information and the correspondence,the quantity of REs occupied by the demodulation reference signal.

Optionally, the waveform may be a channel waveform, or may be a signalwaveform. For example, the channel waveform may be a waveform of aphysical uplink data channel, a waveform of a physical uplink controlchannel, a waveform of a physical downlink data channel, or a waveformof a physical downlink control channel. For example, the signal waveformmay be a waveform of a reference signal, such as a waveform of ademodulation reference signal.

Optionally, the waveform may be a single-carrier waveform or amulti-carrier waveform. Optionally, the waveform may be used to indicatewhether transform precoding is enabled or the like. Optionally, thewaveform may include a cyclic prefix (CP)-orthogonal frequency divisionmultiplexing (OFDM) waveform and/or a discrete Fouriertransform-spread-orthogonal frequency division multiplexing (discreteFourier transform-spread-OFDM, DFT-s-OFDM) waveform.

A relationship between a data block, a demodulation reference signal,and DCI is as follows: The DCI is DCI used to schedule the data block,and the demodulation reference signal is a demodulation reference signalused to transmit the data block or a demodulation reference signal senton a time-frequency resource scheduled by the DCI.

In this embodiment of this application, the base station 110 does notsend, to the UE 120, information about a code division multiplexinggroup (code division multiplexing (ed/ing) group, CDM group) in which anantenna port corresponding to the DMRS is located, and the UE 120 mayalso determine, based on the at least one type of information and thecorrespondence between the at least one type of information and thequantity of REs occupied by the demodulation reference signal, thequantity of REs occupied by the demodulation reference signal.

Optionally, the correspondence configured on the UE 120 may beconfigured by the UE 120, for example, predefined according to aprotocol, or may be configured by the UE 120 after the UE 120 receivesthe correspondence from the base station no, for example, determined viasignaling received from the base station.

For ease of subsequent description, the at least one type of informationis referred to as first information. In other words, the firstinformation may include at least one type of the following information:the DCI format, the configuration type of the demodulation referencesignal, the quantity of symbols occupied by the demodulation referencesignal, the waveform, the RNTI scrambling manner of the DCI, thequantity of symbols occupied by the data block, and the position of thesymbol occupied by the data block.

For ease of subsequent description, quantity of REs occupied by ademodulation reference signal is referred to as a demodulation referencesignal RE overhead, or may be briefly referred to as a demodulationreference signal overhead.

For example, if the quantity of REs occupied by the demodulationreference signal is 8, it indicates that the demodulation referencesignal occupies 8 REs; and/or if the demodulation reference signal REoverhead value is 8, it indicates that the demodulation reference signaloccupies 8 REs; and/or if the demodulation reference signal overhead is8, it indicates that overheads of the demodulation reference signal are8 REs.

Optionally, in this embodiment of this application, a correspondencebetween first information and a demodulation reference signal REoverhead is predefined. An optional manner includes: configuring, forfirst information, a fixed demodulation reference signal RE overheadvalue; or setting a demodulation reference signal RE overhead valueconfigured for the first information to a fixed value.

For example, for a DCI format, a demodulation reference signal REoverhead value may be set to a fixed value 4. Specifically, thefollowing may be predefined: When the DCI format is DCI format 1_0, theDMRS RE overhead value is 4. This may indicate that the demodulationreference signal RE overhead value is fixed to 4 for DCI format 1_0.

For example, the following is predefined: When the DCI format is DCIformat 0_0, the DMRS RE overhead value is 6. This may indicate that thedemodulation reference signal RE overhead value is fixed to 6 for DCIformat 0_0.

Optionally, in this embodiment of this application, for receivingremaining minimum system information (RMSI), when the UE receives noradio resource control (RRC) configuration information, the UE maydetermine the demodulation reference signal RE overhead based on aquantity of REs actually used to transmit the DMRS. For example, thedemodulation reference signal RE overhead value may be set to a fixedvalue 4.

Optionally, in this embodiment of this application, for unicast datascheduled when the DCI format is DCI format 1_0 or DCI format 0_0, datascheduled in this manner usually can be transmitted on only one antennaport at one layer. Therefore, if an RRC parameter is configured for theUE, for example, the RRC parameter may be a downlink DMRS configurationtype (for example, DL-DMRS-config-type), a downlink DMRS maximum length(for example, DL-DMRS-max-len), an uplink DMRS configuration type (forexample, UL-DMRS-config-type), and/or an uplink DMRS maximum length (forexample, UL-DMRS-max-len), the UE may determine the demodulationreference signal RE overhead value based on at least one of theforegoing configured RRC parameters. Optionally, in consideration of asimpler and more uniform system design and implementation, a same DMRSRE overhead may be used for data transmission scheduled in a same DCIformat. For example, the same DCI format may be DCI format 0_0 or DCIformat 1_0. In a possible manner, for data transmission scheduled in DCIformat 0_0 or DCI format 1_0, an RE overhead value of a demodulationreference signal on each physical resource block (PRB) is set to a fixedvalue, for example, 4 or 6.

In the method in this embodiment of this application, optionally, firstinformation may be in a one-to-one correspondence with demodulationreference signal RE overhead. In this way, the base station 110 and theUE 120 can obtain a demodulation reference signal RE overhead valuebased on a correspondence between first information and a demodulationreference signal RE overhead value only by obtaining the firstinformation.

The following describes how to predefine the correspondence betweenfirst information and a demodulation reference signal RE overhead value,in other words, how to predefine a specific quantity of REs occupied bythe demodulation reference signal corresponding to a type of firstinformation. The correspondence between first information and ademodulation reference signal RE overhead value may include at least oneof the following manners:

In a possible design manner, the first information includes the DCIformat. In other words, the base station and/or the UE may obtain, basedon the DCI format, a quantity, corresponding to the DCI format, of REsoccupied by the demodulation reference signal. There is a correspondencebetween the DCI format and the quantity of REs occupied by thedemodulation reference signal.

Optionally, correspondences between one or more DCI formats and DMRS REoverhead values may be predefined. The correspondence between a DCI anda DMRS RE overhead value may be pre-configured on the base station, andthe correspondence may also be pre-configured on the UE, or thecorrespondence may be configured based on signaling after the signalingis received from the base station.

Optionally, the downlink control information format may be used todistinguish between different functions of downlink control information,or may be used to distinguish between content and/or quantities of bitsof downlink control information.

Optionally, different functions of downlink control information mayindicate control information used to schedule uplink data or controlinformation used to schedule downlink data, control information in afallback mode or control information in a normal mode, shortened controlinformation or normal control information, control information used forsingle-codeword scheduling or control information used formulti-codeword scheduling, and/or control information used for open-loopdata scheduling or control information used for closed-loop datascheduling, and/or the like.

For example, format 1_0 may be a format of the control information usedto schedule downlink data, and format 0_0 may be a format of the controlinformation used to schedule uplink data.

For example, format 1_0 is a format of control information used toschedule downlink data in the fallback mode, a format of controlinformation used to schedule downlink data in a shortened mode, and/or aformat of control information that is used to schedule downlink data andthat occupies a relatively small quantity of bits; and format 1_1 is aformat of control information used to schedule downlink data in thenormal mode and/or a format of control information that is used toschedule downlink data and that occupies a relatively large quantity ofbits.

For example, format 0_0 is a format of control information used toschedule uplink data in the fallback mode, a format of controlinformation used to schedule uplink data in a shortened mode, and/or aformat of control information that is used to schedule uplink data andthat occupies a relatively small quantity of bits; and format 0_1 is aformat of control information used to schedule uplink data in the normalmode and/or a format of control information that is used to scheduleuplink data and that occupies a relatively large quantity of bits.

For example, the following may be predefined: When the DCI format is afallback (fallback) DCI format, the DMRS RE overhead value is X, where Xis an integer.

For example, the following may be predefined: When the DCI format is DCIformat 0_0 or DCI format 1_0, the DMRS RE overhead is X. Optionally, avalue of X may be any one of 4, 6, 8, 12, 16, 24, or the like.

Optionally, a DMRS RE overhead predefined for a format of DCI used toschedule uplink data transmission may be the same as a DMRS RE overheadpredefined for a format of DCI used to schedule downlink datatransmission.

For example, the following may be predefined: When the DCI format is DCIformat 1_0, the DMRS RE overhead value is 4; or when the DCI format isDCI format 0_0, the DMRS RE overhead value is 4.

For example, the following may be predefined: When the DCI format is DCIformat 1_0, the DMRS RE overhead value is 6; or when the DCI format isDCI format 0_0, the DMRS RE overhead value is 6.

Optionally, a DMRS RE overhead predefined for a format of DCI used toschedule uplink data transmission may be different from a DMRS REoverhead predefined for a format of DCI used to schedule downlink datatransmission. For example, the following may be predefined: When the DCIformat is the format of the DCI used to schedule downlink datatransmission, the DMRS RE overhead value is X1; or when the DCI formatis the format of the DCI used to schedule uplink data transmission, theDMRS RE overhead value is X2, where both X1 and X2 are integers. A valueof X1 and/or X2 may be any one of 4, 6, 8, 12, 16, 24, and the like.

For example, the following may be predefined: When the DCI format is DCIformat 1_0, the DMRS RE overhead value is 4; or when the DCI format isDCI format 0_0, the DMRS RE overhead value is 6. Optionally, a pluralityof DMRS RE overheads may be alternatively predefined for a same DCIformat. In this case, the base station no may inform, via signaling, theUE 120 of which of the plurality of values should be used to calculate aTBS.

For example, the DMRS RE overhead values predefined for a same DCIformat include 4, 6, 8, 12, or the like. The base station 110 informs,via higher layer signaling or physical layer signaling, the UE 120 thatthe DMRS RE overhead value 6 is used to calculate a TBS.

Optionally, a plurality of correspondences between one downlink controlinformation format and DMRS RE overhead may be predefined. The basestation may inform, via signaling, the UE which correspondence should beused to calculate a TBS.

For example, a correspondence between format 0_0 and a DMRS RE overheadvalue may include at least one of the following correspondences:

a correspondence x1: format 0_0 corresponds to the DMRS RE overheadvalue 4;

a correspondence x2: format 0_0 corresponds to the DMRS RE overheadvalue 6;

a correspondence x3: format 0_0 corresponds to the DMRS RE overheadvalue 8; and

a correspondence x4: format 0_0 corresponds to the DMRS RE overheadvalue 12.

The base station may inform the UE via higher layer signaling and/orphysical layer signaling of which one of the plurality ofcorrespondences between the format 0_0 and DMRS RE overhead values maybe used to determine a DMRS RE overhead value.

For example, “00” represents the correspondence x1, “01” represents thecorrespondence x2, “10” represents the correspondence x3, and “11”represents the correspondence x4.

For example, a correspondence between format 1_0 and a DMRS RE overheadvalue may include at least one of the following correspondences:

a correspondence x1′: format 1_0 corresponds to the DMRS RE overheadvalue 4;

a correspondence x2′: format 1_0 corresponds to the DMRS RE overheadvalue 6;

a correspondence x3′: format 1_0 corresponds to the DMRS RE overheadvalue 8; and

a correspondence x4′: format 1_0 corresponds to the DMRS RE overheadvalue 8.

The base station may inform the UE via higher layer signaling and/orphysical layer signaling, and one of the plurality of correspondencesbetween the format 1_0 and DMRS RE overhead values may be used todetermine a DMRS RE overhead value.

For example, “00” represents the correspondence x1′, “01” represents thecorrespondence x2′, “10” represents the correspondence x3′, and “11”represents the correspondence x4′.

In a possible design manner, the first information includes theconfiguration type of the demodulation reference signal. To be specific,the base station and the UE may obtain, based on the configuration typeof the demodulation reference signal, a quantity, corresponding to theconfiguration type of the demodulation reference signal, of resourceelements occupied by the demodulation reference signal. There is acorrespondence between the configuration type of the demodulationreference signal and the quantity of resource elements occupied by thedemodulation reference signal.

Optionally, the configuration type of the demodulation reference signalis used to indicate a pattern type of the demodulation reference signaland/or a type of the demodulation reference signal.

Optionally, the pattern type may be a single-carrier pattern or amulti-carrier pattern, or may be a comb-like pattern or an RE pattern.For example, a type 1 corresponds to the comb-like pattern or thesingle-carrier pattern, and a type 2 corresponds to the multi-carrierpattern.

Optionally, the type of the demodulation reference signal may be asingle-carrier demodulation reference signal or a multi-carrierdemodulation reference signal. For example, a type 1 corresponds to thesingle-carrier demodulation reference signal, and a type 2 correspondsto the multi-carrier demodulation reference signal.

For example, one or more correspondence between a DMRS configurationtype and a DMRS RE overhead may be predefined.

For example, the base station no may notify the UE 120 of a DMRSconfiguration type by using a parameter “DMRS-config-type” in higherlayer signaling.

DL-DMRS-config-type or UL-DMRS-config-type may be used to indicate DMRStypes, including a DMRS configuration type 1 and a DMRS configurationtype 2, in other words, may be actually used to indicate informationabout a DMRS pattern.

Optionally, a pattern corresponding to DMRS configuration type 1 isshown in FIG. 2, and a pattern corresponding to DMRS configuration type2 may be shown in FIG. 3. In FIG. 2 and FIG. 3, a grid with slashesrepresents an RE occupied by a DMRS.

In FIG. 2, one RB includes 12 subcarriers and seven symbols, and a DMRSoccupies the first, the third, the fifth, the seventh, the ninth, andthe eleventh REs in the third symbol.

In FIG. 3, one RB includes 12 subcarriers and seven symbols, and a DMRSoccupies the first, the second, the seventh, and the eighth REs in thethird symbol.

Optionally, DMRS configuration types may be classified into an uplinkDMRS configuration type and a downlink DMRS configuration type. Theuplink DMRS configuration type and the downlink DMRS configuration typemay be respectively indicated by using the parameter“UL-DMRS-config-type” and the parameter “DL-DMRS-config-type”, or may beindicated by using a same parameter, or the configuration type of theDMRS may be determined in a predefined manner or another manner. This isnot limited in this application.

An example in which the uplink DMRS configuration type is indicated byusing the parameter “UL-DMRS-config-type”, and the downlink DMRSconfiguration type is indicated by using the parameter“DL-DMRS-config-type” is used below for description.

For example, the following may be predefined: When UL-DMRS-config-type=1or DL-DMRS-config-type=1, a DMRS RE overhead value is Y1; or whenUL-DMRS-config-type=2 or DL-DMRS-config-type=2, a DMRS RE overhead valueis Y2, where Y1 and Y2 are integers.

Optionally, Y1 and/or Y2 may be any value of 4, 6, 8, 12, 16, 24, andthe like.

Optionally, the DMRS transmitted by the base station no and/or the UE120 may be transmitted only on a single antenna port (port). In thiscase, for DMRS configuration type 1, one antenna port may correspond tosix REs, and for DMRS configuration type 2, one antenna port maycorrespond to four REs. Therefore, the following may be predefined: WhenUL-DMRS-config-type=1 or DL-DMRS-config-type=1, the DMRS RE overheadvalue is 6; or when UL-DMRS-config-type=2 or DL-DMRS-config-type=2, theDMRS RE overhead value is 4.

If the configuration parameter UL-DMRS-config-type is 1 or theconfiguration parameter DL-DMRS-config-type is 1, the DMRS configurationtype is DMRS configuration type 1; or if the configuration parameterUL-DMRS-config-type is 2 or the configuration parameterDL-DMRS-config-type is 2, the DMRS configuration type is DMRSconfiguration type 2.

The antenna port is a logical antenna, and one antenna port maycorrespond to data transmission at one layer.

Optionally, one antenna port may correspond to one or more physicalantennas.

Optionally, an antenna port is defined as follows. A channel over whicha symbol on the antenna port is conveyed may be inferred by using achannel over which another symbol on the antenna port is conveyed. Forexample, channels over which different symbols on a same antenna portare conveyed may be the same, may have a linear relationship, or may beobtained by using a difference algorithm. A specific inference manner isnot limited in this application.

That one antenna port corresponds to six REs may be as follows. Ademodulation reference signal of one antenna port occupies six REs, or ademodulation reference signal of one antenna port is transmitted on sixREs.

Optionally, Y1 and/or Y2 may have a plurality of values. When Y1 and/orY2 have/has a plurality of values, the base station no may inform, viasignaling, the UE 120 which one of the plurality of values is the DMRSRE overhead.

For example, the following is predefined: Y1 may be at least one of 6,12, 18, 24, and the like. In this case, the base station 110 may inform,via signaling, the UE 120 which one of 6, 12, 18, and 24 is specificallythe DMRS RE overhead value.

For example, the following is predefined: Y2 may be at least one of 4,8, 12, 16, 20, 24, or the like. In this case, the base station 110 mayinform, via signaling, the UE 120 which one of 4, 8, 12, 16, 20, or 24is specifically the DMRS RE overhead value.

Optionally, a plurality of correspondences between one DMRSconfiguration type and DMRS RE overhead may be predefined. The basestation may inform, via signaling, the UE which correspondence should beused to calculate a TBS.

For example, a correspondence between DMRS configuration type 1 and aDMRS RE overhead value may include at least one of the followingcorrespondences:

a correspondence y1: DMRS configuration type 1 corresponds to the DMRSRE overhead value 6;

a correspondence y2: DMRS configuration type 1 corresponds to the DMRSRE overhead value 12;

a correspondence y3: DMRS configuration type 1 corresponds to the DMRSRE overhead value 18; and

a correspondence y4: DMRS configuration type 1 corresponds to the DMRSRE overhead value 24.

The base station may inform, via higher layer signaling and/or physicallayer signaling, the UE which one of the plurality of correspondencesbetween DMRS configuration type 1 and the DMRS RE overhead values may beused to determine a DMRS RE overhead value.

For example, “00” represents the correspondence y1, “01” represents thecorrespondence y2, “10” represents the correspondence y3, and “11”represents the correspondence y4.

For example, a correspondence between DMRS configuration type 2 and aDMRS RE overhead value may include at least one of the followingcorrespondences:

a correspondence y1′: DMRS configuration type 2 corresponds to the DMRSRE overhead value 4;

a correspondence y2′: DMRS configuration type 2 corresponds to the DMRSRE overhead value 8;

a correspondence y3′: DMRS configuration type 2 corresponds to the DMRSRE overhead value 12; and

a correspondence y4′: DMRS configuration type 2 corresponds to the DMRSRE overhead value 16.

The base station may inform, via higher layer signaling and/or physicallayer signaling, the UE which one of the plurality of correspondencesbetween DMRS configuration type 2 and the DMRS RE overhead values may beused to determine a DMRS RE overhead value.

For example, “00” represents the correspondence y1′, “01” represents thecorrespondence y2′, “10” represents the correspondence y3′, and “11”represents the correspondence y4′.

Optionally, DMRSs of different UEs may be code-division-based (namely,orthogonal sequences), or may be time-frequency-division-based (in otherwords, positions of REs occupied by DMRSs of different UEs aredifferent). When DMRSs of different UEs aretime-frequency-division-based, to reduce interference between the DMRSsof the UEs, data signals are mapped to none of the REs occupied by theDMRSs of the UEs. In other words, all the REs occupied by the DMRSs ofthe UEs need to be bypassed when data mapping is performed. In thiscase, a predefined DMRS RE overhead value should be the sum of RE DMRSoverhead values of all the UEs.

For example, the base station no sends a DMRS to UE 1 on an antenna port1000, sends a DMRS to UE 2 on an antenna port 1001, sends a DMRS to UE 3on an antenna port 1002, and sends a DMRS to UE 4 on an antenna port1003. The DMRSs of the UE 1 and the UE 2 are code-division-based, andthe DMRSs of the UE 3 and the UE 4 are code-division-based. The DMRSs ofthe UE 1 and the UE 3 are time-frequency-division-based, and the DMRSsof the UE 2 and the UE 4 are time-frequency-division-based. To avoidmutual interference between the DMRSs of the UEs, total DMRS REoverheads of the antenna ports 1000, 1001, 1002, and 1003 need to bebypassed when resource mapping is performed on data of the UEs.

For example, the following may be predefined: When UL-DMRS-config-type=1or DL-DMRS-config-type=1, the DMRS RE overhead value is 12 (because oneantenna port may correspond to six REs for DMRS configuration type 1);or when UL-DMRS-config-type =2 or DL-DMRS-config-type=2, the DMRS REoverhead value is 8 (because one antenna port may correspond to four REsfor DMRS configuration type 2).

In a possible design manner, the first information includes theconfiguration type of the demodulation reference signal and the quantityof symbols occupied by the demodulation reference signal. To bespecific, a quantity that is of resource elements occupied by thedemodulation reference signal and that corresponds to the configurationtype of the demodulation reference signal and the quantity of symbolsoccupied by the demodulation reference signal may be obtained based onthe configuration type of the demodulation reference signal and thequantity of symbols occupied by the demodulation reference signal. Thereis a correspondence of the quantity of resource elements occupied by thedemodulation reference signal with the configuration type of thedemodulation reference signal and the quantity of symbols occupied bythe demodulation reference signal.

Optionally, the quantity of symbols occupied by the demodulationreference signal may be a number of symbols occupied by the DMRS, aquantity of symbols of a resource on which the DMRS is located, or anumber of symbols of a resource on which the DMRS is located. Forexample, the DMRS may occupy one symbol, or occupy two symbols.

Optionally, the first information may include the DMRS configurationtype and the quantity of symbols occupied by the DMRS. For example, acorrespondence between a DMRS RE overhead value with parametersDMRS-config-type and DMRS-max-len may be predefined.

DL-DMRS-max-len or UL-DMRS-max-len may be used to indicate a maximumnumber of OFDM symbols occupied by the DMRS, for example, 1 or 2.Optionally, DL-DMRS-max-len or UL-DMRS-max-len may be used to indicateonly a number of symbols occupied by a front load DMRS or a basic DMRS.

For example, the following may be predefined: When UL-DMRS-config-type=1and UL-DMRS-max-len=1, or DL-DMRS-config-type=1 and DL-DMRS-max-len=1,the DMRS RE overhead value is Z1, where Z1 is an integer.

For example, the following may be predefined: When UL-DMRS-config-type=1and UL-DMRS-max-len=2, or DL-DMRS-config-type=1 and DL-DMRS-max-len=2,the DMRS RE overhead value is Z2, where Z2 is an integer.

For example, the following may be predefined: When UL-DMRS-config-type=2and UL-DMRS-max-len=1, or DL-DMRS-config-type=2 and DL-DMRS-max-len=1,the DMRS RE overhead value is Z3, where Z3 is an integer.

For example, the following may be predefined: When UL-DMRS-config-type=2and UL-DMRS-max-len=2, or DL-DMRS-config-type=2 and DL-DMRS-max-len=2,the DMRS RE overhead value is Z4, where Z4 is an integer.

Optionally, values of Z1, Z2, Z3, and Z4 may be the same or different.This is not specifically limited. A value of any one of Z1, Z2, Z3, andZ4 may be 4, 6, 8, 12, 16, 18, 24, or the like.

Optionally, UL-DMRS-config-type, DL-DMRS-config-type, UL-DMRS-max-len,and/or DL-DMRS-max-len may be notified by the base station 110 to the UE120 via higher layer signaling, or may be preconfigured on the UE 120.This is not limited herein.

Optionally, for the fallback mode, or for DCI format 0_0 and/or DCIformat 1_0, an uplink DMRS and/or a downlink DMRS may be transmittedonly on a single antenna port. In this case, if the configuration typeof the DMRS is DMRS configuration type 1 and the quantity of symbolsoccupied by the DMRS is 1, one antenna port may correspond to six REs,and the following may be predefined: When UL-DMRS-config-type=1 andUL-DMRS-max-len=1, or when DL-DMRS-config-type=1 and DL-DMRS-max-len=1,the DMRS RE overhead value is 6.

If the configuration type of the DMRS is DMRS configuration type 1 andthe quantity of symbols occupied by the DMRS is 2, one antenna port maycorrespond to 12 REs, and the following may be predefined: WhenUL-DMRS-config-type=1 and UL-DMRS-max-len=2, or whenDL-DMRS-config-type=1 and DL-DMRS-max-len=2, the DMRS RE overhead valueis 12.

If the configuration type of the DMRS is DMRS configuration type 2 andthe quantity of symbols occupied by the DMRS is 1, one antenna port maycorrespond to four REs, and the following may be predefined: WhenUL-DMRS-config-type=2 and UL-DMRS-max-len=1, or whenDL-DMRS-config-type=2 and DL-DMRS-max-len=1, the DMRS RE overhead valueis 4.

If the configuration type of the DMRS is DMRS configuration type 2 andthe quantity of symbols occupied by the DMRS is 2, one antenna port maycorrespond to eight REs, and the following may be predefined: WhenUL-DMRS-config-type=2 and UL-DMRS-max-len=2, or whenDL-DMRS-config-type=2 and DL-DMRS-max-len=2, the DMRS RE overhead valueis 8.

Optionally, DMRSs of different UEs may be code-division-based (namely,orthogonal sequences), or may be time-frequency-division-based (in otherwords, positions of REs occupied by DMRSs of different UEs aredifferent). When time-frequency division is performed on DMRSs ofdifferent UEs, to reduce mutual interference between the DMRSs of theUEs, data signals are mapped to none of the REs occupied by the DMRSs ofthe UEs. In other words, all the REs occupied by the DMRSs of the UEsneed to be bypassed when data mapping is performed. In this case, apredefined DMRS RE overhead value should be the sum of DMRS RE overheadvalues of all the UEs.

For example, the base station no sends a DMRS to UE 1 on an antenna port1000, sends a DMRS to UE 2 on an antenna port 1001, sends a DMRS to UE 3on an antenna port 1002, and sends a DMRS to UE 4 on an antenna port1003. The DMRSs of the UE 1 and the UE 2 are code-division-based, andthe DMRSs of the UE 3 and the UE 4 are code-division-based. The DMRSs ofthe UE 1 and the UE 3 are time-frequency-division-based, and the DMRSsof the UE 2 and the UE 4 are time-frequency-division-based. To avoidmutual interference between the DMRSs of the UEs, all REs occupied bythe DMRSs on the antenna ports 1000, 1001, 1002, and 1003 need to bebypassed when resource mapping is performed on data of the UEs.

For example, if the configuration type of the DMRS is DMRS configurationtype 1 and the quantity of symbols occupied by the DMRS is 1, one portmay correspond to six REs, and the following may be predefined: WhenUL-DMRS-config-type=1 and UL-DMRS-max-len=1, or whenDL-DMRS-config-type=1 and DL-DMRS-max-len=1, the DMRS RE overhead value12.

For example, if the configuration type of the DMRS is DMRS configurationtype 1 and the quantity of symbols occupied by the DMRS is 2, one portmay correspond to 12 REs, and the following may be predefined: WhenUL-DMRS-config-type=1 and UL-DMRS-max-len=2, or whenDL-DMRS-config-type=1 and DL-DMRS-max-len=2, the DMRS RE overhead valueis 24.

For example, if the configuration type of the DMRS is DMRS configurationtype 2 and the quantity of symbols occupied by the DMRS is 1, one portmay correspond to four REs, and the following may be predefined: WhenUL-DMRS-config-type=2 and UL-DMRS-max-len=1, or whenDL-DMRS-config-type=2 and DL-DMRS-max-len=1, the DMRS RE overhead valueis 8.

For example, if the configuration type of the DMRS is DMRS configurationtype 2 and the quantity of symbols occupied by the DMRS is 2, one portmay correspond to eight REs, and the following may be predefined: WhenUL-DMRS-config-type=2 and UL-DMRS-max-len=2, or whenDL-DMRS-config-type=2 and DL-DMRS-max-len=2, the DMRS RE overhead valueis 16.

Optionally, at least one of Z1, Z2, Z3, and Z4 may have a plurality ofvalues. When one of Z1, Z2, Z3, and Z4 has a plurality of values, thebase station no may inform, via signaling, the UE 120 of a specific DMRSRE overhead value.

For example, when values/a value of Z1 and/or Z2 may be selected from 6,12, 18, and 24, the base station no may inform, via signaling, the UE120 which one of 6, 12, 18, and 24 is specifically the DMRS RE overheadvalue.

For example, when values/a value of Z3 and/or Z4 may be selected from 4,8, 12, 16, 20, and 24, the base station no may inform, via signaling,the UE 120 of which one of 4, 8, 12, 16, 20, or 24 is specifically theDMRS RE overhead value.

Optionally, a plurality of correspondences between one demodulationreference signal configuration type and one quantity of symbols occupiedby demodulation reference signal, and DMRS RE overhead may bepredefined. The base station may inform, via signaling, the UE of whichcorrespondence should be used to calculate a TBS.

For example, a correspondence between demodulation reference signalconfiguration type 1 and quantity of symbols occupied by demodulationreference signal 1, and a DMRS RE overhead value may include at leastone of the following correspondences

a correspondence z1: DMRS configuration type 1 and quantity of symbolsoccupied by DMRS 1 correspond to the DMRS RE overhead value 6

a correspondence z2: DMRS configuration type 1 and quantity of symbolsoccupied by DMRS 1 correspond to the DMRS RE overhead value 12

a correspondence z3: DMRS configuration type 1 and quantity of symbolsoccupied by DMRS 1 correspond to the DMRS RE overhead value 18; and

a correspondence z4: DMRS configuration type 1 and quantity of symbolsoccupied by DMRS 1 correspond to the DMRS RE overhead value 24.

The base station may inform, via higher layer signaling and/or physicallayer signaling, the UE of which one of the plurality of correspondencesbetween DMRS configuration type 1 and quantity of symbols occupied byDMRS 1, and DMRS RE overhead values may be used to determine thequantity of DMRSs.

For example, “00” represents the correspondence z1, “01” represents thecorrespondence z2, “10” represents the correspondence z3, and “11”represents the correspondence z4.

For example, a correspondence between demodulation reference signalconfiguration type 1 and quantity of symbols occupied by demodulationreference signal 2, and a DMRS RE overhead value may include at leastone of the following correspondences

a correspondence z1′: DMRS configuration type 1 and quantity of symbolsoccupied by DMRS 2 correspond to the DMRS RE overhead value 12

a correspondence z2′: DMRS configuration type 1 and quantity of symbolsoccupied by DMRS 2 correspond to the DMRS RE overhead value 18

a correspondence z3′: DMRS configuration type 1 and quantity of symbolsoccupied by DMRS 2 correspond to the DMRS RE overhead value 24; and

a correspondence z4′: DMRS configuration type 1 and quantity of symbolsoccupied by DMRS 2 correspond to a DMRS RE overhead value 36.

The base station may inform, via higher layer signaling and/or physicallayer signaling, the UE of which one of the plurality of correspondencesbetween DMRS configuration type 1 and quantity of symbols occupied byDMRS 2, and the DMRS RE overhead values may be used to determine aquantity of REs of a DMRS.

For example, “00” represents the correspondence z1′, “01” represents thecorrespondence z2′, “10” represents the correspondence z3′, and “11”represents the correspondence z4′.

For example, a correspondence between demodulation reference signalconfiguration type 2 and quantity of symbols occupied by demodulationreference signal 1, and a DMRS RE overhead value may include at leastone of the following correspondences:

a correspondence z1″: DMRS configuration type 2 and quantity of symbolsoccupied by DMRS 1 correspond to the DMRS RE overhead value 4;

a correspondence z2″: DMRS configuration type 2 and quantity of symbolsoccupied by DMRS 1 correspond to the DMRS RE overhead value 8;

a correspondence z3″: DMRS configuration type 2 and quantity of symbolsoccupied by DMRS 1 correspond to the DMRS RE overhead value 12; and

a correspondence z4″: DMRS configuration type 2 and quantity of symbolsoccupied by DMRS 1 correspond to the DMRS RE overhead value 16.

The base station may inform, via higher layer signaling and/or physicallayer signaling, the UE of which one of the plurality of correspondencesbetween DMRS configuration type 2 and quantity of symbols occupied byDMRS 1, and the DMRS RE overhead values may be used to determine a DMRSRE overhead value.

For example, “00” represents the correspondence z1″, “01” represents thecorrespondence z2″, “10” represents the correspondence z3″, and “11”represents the correspondence z4″.

For example, a correspondence between demodulation reference signalconfiguration type 2 and quantity of symbols occupied by demodulationreference signal 2, and a DMRS RE overhead value may include at leastone of the following correspondences:

a correspondence z1″′: DMRS configuration type 2 and quantity of symbolsoccupied by DMRS 2 correspond to the DMRS RE overhead value 8;

a correspondence z2″′: DMRS configuration type 2 and quantity of symbolsoccupied by DMRS 2 correspond to the DMRS RE overhead value 16;

a correspondence z3″′: DMRS configuration type 2 and quantity of symbolsoccupied by DMRS 2 correspond to the DMRS RE overhead value 24; and

a correspondence z4″′: DMRS configuration type 2 and quantity of symbolsoccupied by DMRS 2 correspond to a DMRS RE overhead value 32.

The base station may inform, via higher layer signaling and/or physicallayer signaling, the UE which one of the plurality of correspondencesbetween DMRS configuration type 2 and quantity of symbols occupied byDMRS 2, and the DMRS RE overhead values may be used to determine a DMRSRE overhead value.

For example, “00” represents the correspondence z1″′, “01” representsthe correspondence z2″′, “10” represents the correspondence z3″′, and“11” represents the correspondence z4″′.

In a possible design manner, the first information may include awaveform. To be specific, a quantity, corresponding to the waveform, ofresource elements occupied by the demodulation reference signal may beobtained based on the waveform. There is a correspondence between thewaveform and the quantity of resource elements occupied by thedemodulation reference signal.

Optionally, a correspondence between the waveform and a DMRS RE overheadmay be predefined.

Optionally, the waveform may be a channel waveform, or may be a signalwaveform. For example, the channel waveform may be a waveform of aphysical uplink data channel, a waveform of a physical uplink controlchannel, a waveform of a physical downlink data channel, or a waveformof a physical downlink control channel. For example, the signal waveformmay be a waveform of a reference signal, such as a waveform of ademodulation reference signal.

Optionally, the waveform may be classified into a single-carrierwaveform and a multi-carrier waveform. Optionally, the waveform may beused to indicate whether transform precoding is enabled or the like.

For example, the following may be predefined: When the waveform is asingle carrier waveform, that is, when transform precoding is enabled,the DMRS RE overhead value is W1, where W1 is an integer.

For example, the following may be predefined: When the waveform is asingle carrier and only a DMRS of a configuration type 1 is supported ina case of the single carrier, the DMRS RE overhead value is 6.

For example, the following may be predefined: When the waveform is amulti-carrier, that is, transform precoding is not enabled, the DMRS REoverhead value is W2, where W2 is an integer.

For example, the following may be predefined: When the waveform is amulti-carrier, and a DMRS of a configuration type 2 may be supported ina case of the multi-carrier, the DMRS RE overhead value is 4.

For example, the following may be predefined: When the waveform is amulti-carrier, and a DMRS of a configuration type 1 may be supported ina case of the multi-carrier, the DMRS RE overhead value is 6.

Optionally, a value of W1 and/or W2 may be any one of 4, 6, 8, 12, 16,24, and the like.

Optionally, W1 and/or W2 may have a plurality of values. When W1 and/orW2 have/has a plurality of values, the base station no may inform, viasignaling, the UE 120 which one of the plurality of values is the DMRSRE overhead value.

For example, the following is predefined: Wi may be at least one of 6,12, 18, 24, and the like. In this case, the base station no may inform,via signaling, the UE 120 which one of 6, 12, 18, and 24 is specificallythe DMRS RE overhead value.

For example, the following is predefined: W2 may be at least one of 4,8, 12, 16, 20, 24, or the like. In this case, the base station no mayinform, via signaling, the UE 120 which one of 4, 8, 12, 16, 20, or 24is specifically the DMRS RE overhead value.

Optionally, a plurality of correspondences between one waveform and DMRSRE overhead values may be predefined. The base station may inform, viasignaling, the UE which correspondence should be used to calculate aTBS.

For example, a correspondence between a waveform and a DMRS RE overheadvalue may include at least one of the following correspondences:

a correspondence w1: a case in which transform precoding is not enabledcorresponds to the DMRS RE overhead value 4;

a correspondence w2: a case in which transform precoding is not enabledcorresponds to the DMRS RE overhead value 8;

a correspondence w3: a case in which transform precoding is enabledcorresponds to the DMRS RE overhead value 6; and

correspondence w4: a case in which transform precoding is enabledcorresponds to the DMRS RE overhead value 12.

The base station may inform, via higher layer signaling and/or physicallayer signaling, the UE of which one of the plurality of correspondencesbetween a waveform and DMRS RE overhead values may be used to determinea DMRS RE overhead value.

For example, “00” represents the correspondence w1, “01” represents thecorrespondence w2, “10” represents the correspondence w3, and “11”represents the correspondence w4.

In a possible implementation, the first information may include awaveform and a quantity of symbols occupied by the demodulationreference signal. To be specific, a quantity, corresponding to thewaveform and the quantity of symbols occupied by the demodulationreference signal, of resource elements occupied by the demodulationreference signal may be obtained based on the waveform and the quantityof symbols occupied by the demodulation reference signal. There is acorrespondence between the waveform and the quantity of symbols occupiedby the demodulation reference signal, and the quantity of resourceelements occupied by the demodulation reference signal.

Optionally, the correspondence between the waveform and the quantity ofsymbols occupied by the DMRS, and a DMRS RE overhead value may bepredefined.

For example, the following may be predefined: When a waveform is asingle carrier waveform and a quantity of symbols occupied by an uplinkDMRS (UL-DMRS-max-len) is 1, the DMRS RE overhead value is W3, where W3is an integer.

For example, the following may be predefined: When the waveform is asingle carrier waveform and UL-DMRS-max-len=1, the DMRS RE overheadvalue is 6.

For example, the following may be predefined: When the waveform is asingle carrier waveform and UL-DMRS-max-len=2, the DMRS RE overheadvalue is W4, where W4 is an integer.

For example, the following may be predefined: When the waveform is asingle carrier waveform and UL-DMRS-max-len=2, the DMRS RE overheadvalue is 12.

For example, the following may be predefined: When the waveform is amulti-carrier waveform and a quantity of symbols occupied by a downlinkDMRS (DL-DMRS-max-len) is 1, or when the waveform is a multi-carrierwaveform and UL-DMRS-max-len=1, the DMRS RE overhead value is W5, whereW5 is an integer.

For example, the following may be predefined: When the waveform is amulti-carrier waveform and DL-DMRS-max-len=1, or when the waveform is amulti-carrier waveform and UL-DMRS-max-len=1, the DMRS RE overhead valueis 4.

For example, the following may be predefined: When the waveform is amulti-carrier waveform and DL-DMRS-max-len=2, or when the waveform is amulti-carrier waveform or UL-DMRS-max-len=2, the DMRS RE overhead valueis W6, where W6 is an integer.

For example, the following may be predefined: When the waveform is amulti-carrier waveform and DL-DMRS-max-len=2, or when the waveform is amulti-carrier waveform or UL-DMRS-max-len=2, the DMRS RE overhead valueis 8.

Optionally, a value of W3 or W4 may be any one of 4, 6, 8, 12, 16, 24,and the like.

Optionally, W3 and/or W4 may have a plurality of values. When W3 and/orW4 have/has a plurality of values, the base station no may inform, viasignaling, the UE 120 which one of the plurality of values is the DMRSRE overhead value.

For example, the following is predefined: W3 may be at least one of 6,12, 18, 24, and the like. In this case, the base station 110 may inform,via signaling, the UE 120 which one of 6, 12, 18, and 24 is specificallythe DMRS RE overhead value.

For example, the following is predefined: W4 may be at least one of 4,8, 12, 16, 20, 24, or the like. In this case, the base station no mayinform, via signaling, the UE 120 which one of 4, 8, 12, 16, 20, or 24is specifically the DMRS RE overhead value.

Optionally, a plurality of correspondences between one waveform and onequantity of symbols occupied by DMRS, and DMRS RE overhead values may bepredefined. The base station may inform, via signaling, the UE whichcorrespondence should be used to calculate a TBS.

For example, a correspondence between a waveform with transformprecoding not enabled and quantity of symbols occupied by DMRS 1, and aDMRS RE overhead value may include at least one of the followingcorrespondences:

a correspondence w1′: a case in which transform precoding is not enabledand a quantity of symbols occupied by DMRS is 1 corresponds to the DMRSRE overhead value 4;

a correspondence w2′: a case in which transform precoding is not enabledand a quantity of symbols occupied by DMRS is 1 corresponds to the DMRSRE overhead value 8;

a correspondence w3: a case in which transform precoding is not enabledand a quantity of symbols occupied by DMRS is 1 corresponds to the DMRSRE overhead value 12; and

a correspondence w4′: a case in which transform precoding is not enabledand a quantity of symbols occupied by DMRS is 1 corresponds to the DMRSRE overhead value 16.

The base station may inform, via higher layer signaling and/or physicallayer signaling, the UE which one of the plurality of correspondencesbetween a waveform and DMRS RE overhead values may be used to determinea DMRS RE overhead value.

For example, “00” represents the correspondence w1′, “01” represents thecorrespondence w2′, “10” represents the correspondence w3′, and “11”represents the correspondence w4′.

For example, a correspondence between a waveform with transformprecoding not enabled and quantity of symbols occupied by DMRS 2, and aDMRS RE overhead value may include at least one of the followingcorrespondences:

a correspondence w1″: a case in which transform precoding is not enabledand a quantity of symbols occupied by DMRS is 2 corresponds to the DMRSRE overhead value 8;

a correspondence w2″: a case in which transform precoding is not enabledand a quantity of symbols occupied by DMRS is 2 corresponds to the DMRSRE overhead value 16;

a correspondence w3″: a case in which transform precoding is not enabledand a quantity of symbols occupied by DMRS is 2 corresponds to the DMRSRE overhead value 24; and

correspondence w4″: a case in which transform precoding is not enabledand a quantity of symbols occupied by DMRS is 2 corresponds to a DMRS REoverhead value 36.

The base station may inform, via higher layer signaling and/or physicallayer signaling, the UE which one of the plurality of correspondencesbetween a waveform and DMRS RE overhead values may be used to determinea DMRS RE overhead value.

For example, “00” represents the correspondence w1″, “01” represents thecorrespondence w2″, “10” represents the correspondence w3″, and “11”represents the correspondence w4″.

For example, a correspondence between a waveform with transformprecoding enabled and quantity of symbols occupied by DMRS 1, and a DMRSRE overhead value may include at least one of the followingcorrespondences:

a correspondence w1″′: a case in which transform precoding is enabledand a quantity of symbols occupied by DMRS is 1 corresponds to the DMRSRE overhead value 6;

a correspondence w2″′: a case in which transform precoding is enabledand a quantity of symbols occupied by DMRS is 1 corresponds to the DMRSRE overhead value 12;

correspondence w3″′: a case in which transform precoding is enabled anda quantity of symbols occupied by DMRS is 1 corresponds to the DMRS REoverhead value 18; and

correspondence w4″′: a case in which transform precoding is enabled anda quantity of symbols occupied by DMRS is 1 corresponds to the DMRS REoverhead value 24.

The base station may inform, via higher layer signaling and/or physicallayer signaling, the UE which one of the plurality of correspondencesbetween a waveform and DMRS RE overhead values may be used to determinea DMRS RE overhead value.

For example, “00” represents the correspondence w1″′, “01” representsthe correspondence w2″′, “10” represents the correspondence w3″′, and“11” represents the correspondence w4″.

For example, a correspondence between a waveform with transformprecoding enabled and quantity of symbols occupied by DMRS 2, and a DMRSRE overhead value may include at least one of the followingcorrespondences:

a correspondence w1″″: a case in which transform precoding is enabledand a quantity of symbols occupied by DMRS is 2 corresponds to the DMRSRE overhead value 12;

a correspondence w2″″: a case in which transform precoding is enabledand a quantity of symbols occupied by DMRS is 2 corresponds to the DMRSRE overhead value 24;

a correspondence w3″″: a case in which transform precoding is enabledand a quantity of symbols occupied by DMRS is 2 corresponds to a DMRS REoverhead value 36; and

correspondence w4″″: a case in which transform precoding is enabled anda quantity of symbols occupied by DMRS is 2 corresponds to a DMRS REoverhead value 48.

The base station may inform, via higher layer signaling and/or physicallayer signaling, the UE which one of the plurality of correspondencesbetween a waveform and DMRS RE overhead values may be used to determinea DMRS RE overhead value.

For example, “00” represents the correspondence w1″″, “01” representsthe correspondence w2″″, “10” represents the correspondence w3″″, and“11” represents the correspondence w4″″.

In a possible design manner, the first information may include awaveform, the configuration type of the demodulation reference signal,and the quantity of symbols occupied by the demodulation referencesignal. To be specific, a demodulation reference signal RE overhead maybe obtained based on the waveform, the configuration type of thedemodulation reference signal, and the quantity of symbols occupied bythe demodulation reference signal. There is a correspondence between thedemodulation reference signal RE overhead value, and the waveform, theconfiguration type of the demodulation reference signal, and thequantity of symbols occupied by the demodulation reference signal.

Optionally, the first information may include a waveform, theconfiguration type of the DMRS, and the quantity of symbols occupied bythe DMRS, and the correspondence between the DMRS RE overhead value, andthe waveform, the configuration type of the DMRS, and the quantity ofsymbols occupied by the DMRS may be predefined.

For example, the following may be predefined: When the waveform is amulti-carrier waveform, DL-DMRS-config-type=1, and DL-DMRS-max-len=1, orwhen the waveform is a multi-carrier waveform, UL-DMRS-config-type=1,and UL-DMRS-max-len=1, the DMRS RE overhead value is W7, and W7 is aninteger.

For example, the following may be predefined: When the waveform is amulti-carrier waveform, DL-DMRS-config-type=1, and DL-DMRS-max-len=1, orwhen the waveform is a multi-carrier waveform, UL-DMRS-config-type=1,and UL-DMRS-max-len=1, the DMRS RE overhead value is 6.

For example, the following may be predefined: When the waveform is amulti-carrier waveform, DL-DMRS-config-type=1, and DL-DMRS-max-len=2, orwhen the waveform is a multi-carrier waveform, UL-DMRS-config-type=1,and UL-DMRS-max-len=2, the DMRS RE overhead value is W8, where W8 is aninteger.

For example, the following may be predefined: When the waveform is amulti-carrier waveform, DL-DMRS-config-type=1, and DL-DMRS-max-len=2, orwhen the waveform is a multi-carrier waveform, UL-DMRS-config-type=1,and UL-DMRS-max-len=2, the DMRS RE overhead value is 12.

For example, the following may be predefined: When the waveform is amulti-carrier waveform, DL-DMRS-config-type=2, and DL-DMRS-max-len=1, orwhen the waveform is a multi-carrier waveform, UL-DMRS-config-type=2,and UL-DMRS-max-len=1, the DMRS RE overhead value is W9, where W9 is aninteger. In this case, an example of W9 is 4.

For example, the following may be predefined: When the waveform is amulti-carrier waveform, DL-DMRS-config-type=2, and DL-DMRS-max-len=2, orwhen the waveform is a multi-carrier waveform, UL-DMRS-config-type=2,and UL-DMRS-max-len=2, the DMRS RE overhead value is W10, where W10 isan integer. An example of W10 is 8.

Optionally, a value of any one of W1 to W10 may be 4, 6, 8, 12, 16, 18,24, 36, 48, or the like. Values of any two of W1 to W10 may be the same,or may be different. This is not limited.

Optionally, DMRSs of different UEs may be code-division-based (namely,orthogonal sequences), or may be time-frequency-division-based (in otherwords, positions of REs occupied by DMRSs of different UEs aredifferent). When time-frequency division is performed on DMRSs ofdifferent UEs, to reduce mutual interference between the DMRSs of theUEs, data signals are mapped to none of the REs occupied by the DMRSs ofthe UEs. In other words, all the REs occupied by the DMRSs of the UEsneed to be bypassed when data mapping is performed. In this case, apredefined DMRS RE overhead value should be the sum of DMRS RE overheadvalues of all the UEs.

For example, the base station no sends a DMRS to UE 1 on an antenna port1000, sends a DMRS to UE 2 on an antenna port 1001, sends a DMRS to UE 3on an antenna port 1002, and sends a DMRS to UE 4 on an antenna port1003. The DMRSs of the UE 1 and the UE 2 are code-division-based, andthe DMRSs of the UE 3 and the UE 4 are code-division-based. The DMRSs ofthe UE 1 and the UE 3 are time-frequency-division-based, and the DMRSsof the UE 2 and the UE 4 are time-frequency-division-based. To avoidmutual interference between the DMRSs of the UEs, all REs occupied bythe DMRSs on the antenna ports 1000, 1001, 1002, and 1003 need to bebypassed when resource mapping is performed on data of the UEs.

For example, if the configuration type of the DMRS is DMRS configurationtype 1, one port may correspond to six REs, and the following may bepredefined: When the waveform is a multi-carrier waveform,UL-DMRS-config-type=1, and UL-DMRS-max-len=1, or when the waveform is amulti-carrier waveform, DL-DMRS-config-type=1, and DL-DMRS-max-len=1,the DMRS RE overhead value is 12.

For example, if the configuration type of the DMRS is DMRS configurationtype 1, one port may correspond to 12 REs, and the following may bepredefined: When the waveform is a multi-carrier waveform,UL-DMRS-config-type=1, and UL-DMRS-max-len=2, or when the waveform is amulti-carrier waveform, DL-DMRS-config-type=1, and DL-DMRS-max-len=2,the DMRS RE overhead value is 24.

For example, if the configuration type of the DMRS is DMRS configurationtype 2, one port may correspond to four REs, and the following may bepredefined: When the waveform is a multi-carrier waveform,UL-DMRS-config-type=2, and UL-DMRS-max-len=1, or when the waveform is amulti-carrier waveform, DL-DMRS-config-type=2, and DL-DMRS-max-len=1,the DMRS RE overhead value is 8.

For example, if the configuration type of the DMRS is DMRS configurationtype 2, one port may correspond to eight REs, and the following may bepredefined: When the waveform is a multi-carrier waveform,UL-DMRS-config-type=2, and UL-DMRS-max-len=2, or when the waveform is amulti-carrier waveform, DL-DMRS-config-type=2, and DL-DMRS-max-len=2,the DMRS RE overhead value is 16.

Optionally, the following may be predefined: Any one of W1 to W10 has aplurality of values. When the following is predefined: any one of W1 toW10 has a plurality of values, the base station may inform, viasignaling, the UE of a specific DMRS RE overhead value.

For example, if the following is predefined: at least one of W1 to W8may be 6, 12, 18, 24, or the like, the base station may inform, viasignaling, the UE which one of 6, 12, 18, or 24 is specifically the DMRSRE overhead value.

For example, if the following is predefined: any one of W2, W4, W5, W9or Wio may be 4, 8, 12, 16, 20, 24, or the like, the base station mayinform, via signaling, the UE which one of 4, 8, 12, 16, 20, and 24 isspecifically the DMRS RE overhead value.

In a possible design manner, the first information may include the typeof the data channel and/or the radio network temporary identifier (RNTI)scrambling manner of the downlink control information. To be specific, ademodulation reference signal RE overhead value may be obtained based onthe type of the data channel and/or the RNTI scrambling manner of thedownlink control information. There is a correspondence between the typeof the data channel and/or the RNTI scrambling manner of the downlinkcontrol information, and the demodulation reference signal RE overheadvalue.

Optionally, the correspondence between the type of the data channeland/or the RNTI scrambling manner of the DCI, and the DMRS RE overheadvalue may be predefined.

There may be a plurality of types of data channels between the basestation and the UE.

Optionally, the type of the data channel may include at least one ofuplink data transmission and downlink data transmission.

Optionally, the type of the data channel includes at least one of systeminformation, broadcast information, unicast information, and multicastinformation.

For example, some physical data shared channels (physical downlinksharing channels, PDSCH) are used to transmit unicast data of UE, somePDSCHs are used to transmit system information, broadcast information,or multicast information, some PDSCHs are used to transmit paging (P)information, and some PDSCHs may be used to transmit a random accessresponse (RAR). The unicast data is UE-specific data, and the multicastinformation or the broadcast information is data that can be received bya plurality of UEs at the same time.

For example, some uplink data shared channels (physical uplink sharingchannel, PUSCH) are used to transmit unicast data of UE, and some PUSCHsare used to transmit a random access message 3.

For example, a communication procedure is as follows. User equipmentfirstly performs downlink synchronization, receives a downlinksynchronization signal, enters an RRC connected mode, then receives RRCsignaling and physical layer signaling, and perform downlink datatransmission. In addition, after entering the RRC connected mode, theuser equipment may perform uplink random access. The base station sendsa random access response, and the user equipment completes uplinksynchronization and performs uplink data transmission.

For example, the UE needs to receive DCI before receiving a PDSCH.Information bits of the DCI include a cyclic redundancy check (CRC)code.

Optionally, the CRC may be related to an RNTI. For example, DCI forremaining minimum system information (RMSI) may be scrambled by usingCRC generated based on an RMSI-RNTI. DCI for paging may be scrambled byusing CRC generated based on a P-RNTI. DCI for a RAR may be scrambled byusing CRC generated based on a RA-RNTI. DCI for a user-level datachannel may be scrambled by using CRC generated based on a cell(C)-RNTI.

For example, for a data channel used to transmit RMSI, paging, message3, a RAR, and/or the like, a data channel scheduled by DCI before aradio resource control (RRC) connected mode is entered, or a datachannel scheduled by DCI scrambled based on an RMSI-RNTI, an SI-RNRI, aP-RNTI, or a RA-RNTI, the following may be predefined: The DMRS REoverhead value is 4, 6, or the like.

Optionally, for the data channel used to transmit the RMSI, the paging,the message 3, the RAR, and/or the like, the data channel scheduled bythe DCI before the radio resource control (RRC) connected mode isentered, or the data channel scheduled by the DCI scrambled based on theRMSI-RNTI, the SI-RNRI, the P-RNTI, or the RA-RNTI, the DMRS RE overheadvalue may be predefined on the UE, or may be notified by the basestation.

Optionally, a same DMRS RE overhead value or different DMRS RE overheadvalues may be predefined for different data channels.

For example, for uplink data scheduling, that the DMRS RE overhead valueis 6 may be predefined; and for downlink data scheduling, that the DMRSRE overhead value is 4 may be predefined.

Optionally, a DMRS RE overhead configured on UE for a data channelscheduled after the RRC connected mode is entered and/or a data channelscheduled by DCI scrambled based on a C-RNTI may be predefined on theUE, or may be notified by the base station.

Optionally, a plurality of DMRS RE overheads may be predefined for asame data channel, and then the base station notifies, by signaling, theUE of the DMRS RE overhead.

In a possible design manner, the first information includes the quantityof symbols occupied by the data block. To be specific, a quantity,corresponding to the quantity of symbols occupied by the data block, ofresource elements occupied by the demodulation reference signal may beobtained based on the quantity of symbols occupied by the data block.There is a correspondence between the quantity of symbols occupied bythe data block and the quantity of resource elements occupied by thedemodulation reference signal.

Optionally, a correspondence between the quantity of symbols occupied bythe data block and a DMRS RE overhead may be predefined.

For example, the following may be predefined: When the quantity ofsymbols occupied by the data block is less than 7, the DMRS RE overheadvalue is 4 or 6. This is because when the quantity of symbols occupiedby the data block is less than 7, only a front load DMRS but noadditional DMRS may be transmitted in a time unit (for example, 14symbols) used for data block transmission.

For example, the following may be predefined: When the quantity ofsymbols occupied by the data block is greater than or equal to 7, theDMRS RE overhead value is 8 or 12. This is because when the quantity ofsymbols occupied by the data block is greater than or equal to 7, notonly a front load DMRS but also an additional DMRS may be transmitted ina time unit (for example, 14 symbols) used for data block transmission.

The front load DMRS is a DMRS that occupies a front symbol in DMRSstransmitted in a time unit, and the additional DMRS is a DMRS thatoccupies a rear symbol in the DMRSs transmitted in the time unit.

The front loaded DMRS may also be referred to as a basic DMRS, and maybe placed at a start position or a relative front position of data. Theadditional DMRS may also be referred to as an additional DMRS. The basicDMRS and the additional DMRS may be carried at different symbolpositions of a same scheduling unit. The same scheduling unit includesat least any one of a subframe, a slot, or a mini-slot. This is notspecifically limited in this embodiment of this application.

Optionally, it is specified that the additional DMRS may be used toimprove channel estimation accuracy, and is applicable to a high-speedmoving scenario. When channel status on different symbols changes, theadditional DMRS is introduced to improve the channel estimationaccuracy.

FIG. 4 and FIG. 5 are schematic diagrams of a front loaded DMRS and anadditional DMRS. In FIG. 4 and FIG. 5, a symbol filled with horizontallines is a symbol occupied by a basic DMRS, namely, a symbol occupied bya front-loaded DMRS, and a symbol filled with points is a symboloccupied by an additional DMRS.

In FIG. 4, the front loaded DMRS is on a symbol 3 (namely, the fourthsymbol), and the additional DMRS is on a symbol 7 (namely, the eighthsymbol). In FIG. 5, the front loaded DMRS is on a symbol 2 (namely, thethird symbol), and the additional DMRS is on a symbol 7 (namely, theeighth symbol).

To obtain a more accurate TBS during TBS calculation, a quantity of REsof DMRSs including the front-loaded DMRS and the additional DMRS thatare actually transmitted by the base station needs to be considered whenoverheads of the DMRSs are considered. This is because data is mapped tonone of the REs of the DMRSs.

In a possible design manner, the first information includes the positionof the symbol occupied by the data block. To be specific, a quantity,corresponding to the position of the symbol occupied by the data block,of resource elements occupied by the demodulation reference signal maybe obtained based on the position of the symbol occupied by the datablock. There is a correspondence between the position of the symboloccupied by the data block and the quantity of resource elementsoccupied by the demodulation reference signal.

Optionally, a correspondence between the position of the symbol occupiedby the data block and a DMRS RE overhead may be predefined.

For example, the following may be predefined: When the last symboloccupied by the data block is previous to the ninth symbol in a timeunit (for example, 14 symbols) used for data block transmission, theDMRS RE overhead value is 4 or 6. This is because the quantity ofsymbols occupied by the data block may be less than 7 in this case. Inother words, only a front load DMRS but no additional DMRS may betransmitted in the time unit used for data block transmission.

That the last symbol occupied by the data block is previous to the ninthsymbol in a time unit used for data block transmission may be understoodas follows: An index of the last symbol occupied by the data block isless than 8.

For example, the following may be predefined: When the last symboloccupied by the data block is on or follows the ninth symbol in a timeunit (for example, 14 symbols) used for data block transmission, theDMRS RE overhead value is 8 or 12. This is because the quantity ofsymbols occupied by the data block may be greater than or equal to 7 inthis case. In other words, not only a front load DMRS but also anadditional DMRS may be transmitted in a time unit used for data blocktransmission.

That the last symbol occupied by the data block is on or follows theninth symbol in a time unit used for data block transmission may beunderstood as follows: An index of the last symbol occupied by the datablock is greater than or equal to 8.

In a possible design manner, the first information may include aposition of a symbol occupied by an additional DMRS and/or a quantity(or a number) of additional DMRSs. To be specific, a quantity,corresponding to the position of the symbol occupied by the additionalDMRS and/or the quantity (or the number) of additional DMRSs, ofresource elements occupied by the demodulation reference signal may beobtained based on the position of the symbol occupied by the additionalDMRS and/or the quantity (or the number) of additional DMRSs. There is acorrespondence between the position of the symbol occupied by additionalDMRS and/or the quantity (or the number) of additional DMRSs and thequantity of resource elements occupied by the demodulation referencesignal.

Optionally, a correspondence between the quantity (or the number) ofadditional DMRSs and/or the position of the symbol occupied by theadditional DMRS and a DMRS RE overhead value may be predefined.

DL-DMRS-add-pos or UL-DMRS-add-pos may be used to indicate the quantityof additional DMRSs, or may be used to indicate the number of additionalDMRSs, for example, may be at least one of 0, 1, 2, and 3.

Optionally, when a quantity of symbols occupied by a front load DMRS is1, if the quantity of additional DMRSs is 0, it indicates that there are0 additional-DMRS-occupied symbols; if the quantity of additional DMRSsis 1, it indicates that there is 1 additional-DMRS-occupied symbol; ifthe quantity of additional DMRSs is 2, it indicates that there are 2additional-DMRS-occupied symbols; or if the quantity of additional DMRSsis 3, it indicates that there are 3 additional-DMRS-occupied symbols.

Optionally, when a quantity of symbols occupied by a front load DMRS is2, if the quantity of additional DMRSs is 0, it indicates that there are0 additional-DMRS-occupied symbols; if the quantity of additional DMRSsis 1, it indicates that there are 2 additional-DMRS-occupied symbols; ifthe quantity of additional DMRSs is 2, it indicates that there are 4additional-DMRS-occupied symbols; or if the quantity of additional DMRSsis 3, it indicates that there are 6 additional-DMRS-occupied symbols.

DL-DMRS-add-pos or UL-DMRS-add-pos may also be used to indicate theposition of the symbol occupied by the additional DMRS, for example, maybe at least one of 0, 1, 2, and 3.

Optionally, the position of the symbol occupied by the additional DMRSmay alternatively be understood as follows: The position of the symboloccupied by the additional DMRS is a quantity of front load DMRSpositions, for example, may be at least one of 0, 1, 2, and 3.

Optionally, when a quantity of symbols occupied by a front load DMRS is1, if the position of the symbol occupied by the additional DMRS is 0,it indicates that the additional DMRS occupies 0 front load DMRSpositions, that is, the additional DMRS occupies 0 symbols; if theposition of the symbol occupied by the additional DMRS is 1, itindicates that the additional DMRS occupies 1 front load DMRS position,that is, the additional DMRS occupies 1 symbol; if the position of thesymbol occupied by the additional DMRS is 2, it indicates that theadditional DMRS occupies 2 front load DMRS positions, that is, theadditional DMRS occupies 2 symbols; or if the position of the symboloccupied by the additional DMRS is 3, it indicates that the additionalDMRS occupies 3 front load DMRS positions, that is, the additional DMRSoccupies 3 symbols.

Optionally, when a quantity of symbols occupied by a front load DMRS is2, if the position of the symbol occupied by the additional DMRS is 0,it indicates that the additional DMRS occupies 0 front load DMRSpositions, that is, the additional DMRS occupies 0 symbols; if theposition of the symbol occupied by the additional DMRS is 1, itindicates that the additional DMRS occupies 1 front load DMRS position,that is, the additional DMRS occupies 2 symbols; if the position of thesymbol occupied by the additional DMRS is 2, it indicates that theadditional DMRS occupies 2 front load DMRS positions, that is, theadditional DMRS occupies 4 symbols; or if the position of the symboloccupied by the additional DMRS is 3, it indicates that the additionalDMRS occupies 3 front load DMRS positions, that is, the additional DMRSoccupies 6 symbols.

Optionally, additional DMRSs may be classified into an uplink additionalDMRS and a downlink additional DMRS. A position of a symbol occupied bythe uplink additional DMRS and a position of a symbol occupied by thedownlink additional DMRS may be respectively represented by a parameter“UL-DMRS-add-pos” and a parameter “DL-DMRS-add-pos”.

Optionally, the position of the symbol occupied by the uplink additionalDMRS and the position of the symbol occupied by the downlink additionalDMRS may be indicated by using a same parameter. Details are not limitedin this application.

Optionally, the following may be predefined: When DL-DMRS-add-pos=0 orUL-DMRS-add-pos=0, the DMRS RE overhead value is Q1, where Q1 is aninteger.

For example, the following may be predefined: When DL-DMRS-add-pos=1 orUL-DMRS-add-pos=1, the DMRS RE overhead value is Q2, where Q2 is aninteger.

For example, the following may be predefined: When DL-DMRS-add-pos=2 orUL-DMRS-add-pos=2, the DMRS RE overhead value is Q3, where Q3 is aninteger.

For example, the following may be predefined: When DL-DMRS-add-pos=3 orUL-DMRS-add-pos=3, the DMRS RE overhead value is Q4, where Q4 is aninteger.

For example, the following may be predefined: When DL-DMRS-add-pos=0 orUL-DMRS-add-pos=0, the DMRS RE overhead value is 4 or 6.

For example, the following may be predefined: When DL-DMRS-add-pos=1 orUL-DMRS-add-pos=1, the DMRS RE overhead value is 8 or 12.

For example, the following may be predefined: When DL-DMRS-add-pos=2 orUL-DMRS-add-pos=2, the DMRS RE overhead value is 12 or 18.

For example, the following may be predefined: When DL-DMRS-add-pos=3 orUL-DMRS-add-pos=3, the DMRS RE overhead value is 16 or 24.

Optionally, values of Q1, Q2, Q3, and Q4 may be the same or different.This is not specifically limited. A value of any one of Q1, Q2, Q3, andQ4 may be 4, 6, 8, 12, 16, 18, 24, or the like.

Optionally, at least one of Q1, Q2, Q3, and Q4 may have a plurality ofvalues. When one of Q1, Q2, Q3, and Q4 has a plurality of values, thebase station 110 may inform, via signaling, the UE 120 of a specificDMRS RE overhead value.

In a possible design manner, the first information may include theconfiguration type of the DMRS, the quantity of symbols occupied by theDMRS, and the quantity of symbols occupied by the data block. To bespecific, a quantity, corresponding to the configuration type of theDMRS, the quantity of symbols occupied by the DMRS, and the quantity ofsymbols occupied by the data block, of resource elements occupied by thedemodulation reference signal may be obtained based on the configurationtype of the DMRS, the quantity of symbols occupied by the DMRS, and thequantity of symbols occupied by the data block. There is acorrespondence between the configuration type of the DMRS, the quantityof symbols occupied by the DMRS, and the quantity of symbols occupied bythe data block, and the quantity of resource elements occupied by thedemodulation reference signal.

Optionally, a correspondence between a DMRS RE overhead value, and theconfiguration type of the DMRS, the quantity of symbols occupied by theDMRS, and the quantity of symbols occupied by the data block may bepredefined.

Optionally, for example, the following may be predefined: WhenDL-DMRS-config-type=1, DL-DMRS-max-len=1, and the quantity of symbolsoccupied by the data block is less than 7, or whenUL-DMRS-config-type=1, UL-DMRS-max-len=1, and the quantity of symbolsoccupied by the data block is less than 7, the DMRS RE overhead value isP1, where P1 is an integer.

For example, the following may be predefined: WhenDL-DMRS-config-type=1, DL-DMRS-max-len=2, and the quantity of symbolsoccupied by the data block is less than 7, or whenUL-DMRS-config-type=1, UL-DMRS-max-len=2, and the quantity of symbolsoccupied by the data block is less than 7, the DMRS RE overhead value isP2, where P2 is an integer.

For example, the following may be predefined: WhenDL-DMRS-config-type=2, DL-DMRS-max-len=1, and the quantity of symbolsoccupied by the data block is less than 7, or whenUL-DMRS-config-type=2, UL-DMRS-max-len=1, and the quantity of symbolsoccupied by the data block is less than 7, the DMRS RE overhead value isP3, where P3 is an integer.

For example, the following may be predefined: WhenDL-DMRS-config-type=2, DL-DMRS-max-len=2, and the quantity of symbolsoccupied by the data block is less than 7, or whenUL-DMRS-config-type=2, UL-DMRS-max-len=2, and the quantity of symbolsoccupied by the data block is less than 7, the DMRS RE overhead value isP4, where P4 is an integer.

For example, the following may be predefined: WhenDL-DMRS-config-type=1, DL-DMRS-max-len=1, and the quantity of symbolsoccupied by the data block is greater than or equal to 7, or whenUL-DMRS-config-type=1, UL-DMRS-max-len=1, and the quantity of symbolsoccupied by the data block is greater than or equal to 7, the DMRS REoverhead value is P5, where P5 is an integer.

For example, the following may be predefined: WhenDL-DMRS-config-type=1, DL-DMRS-max-len=2, and the quantity of symbolsoccupied by the data block is greater than or equal to 7, or whenUL-DMRS-config-type=1, UL-DMRS-max-len=2, and the quantity of symbolsoccupied by the data block is greater than or equal to 7, the DMRS REoverhead value is P6, where P6 is an integer.

For example, the following may be predefined: WhenDL-DMRS-config-type=2, DL-DMRS-max-len=1, and the quantity of symbolsoccupied by the data block is greater than or equal to 7, or whenUL-DMRS-config-type=2, UL-DMRS-max-len=1, and the quantity of symbolsoccupied by the data block is greater than or equal to 7, the DMRS REoverhead value is P7, where P7 is an integer.

For example, the following may be predefined: WhenDL-DMRS-config-type=2, DL-DMRS-max-len=2, the quantity of symbolsoccupied by the data block is greater than or equal to 7, or whenUL-DMRS-config-type=2, UL-DMRS-max-len=2, and the quantity of symbolsoccupied by the data block is greater than or equal to 7, the DMRS REoverhead value is P8, where P8 is an integer.

Optionally, a value of any one of P1 to P8 may be 4, 6, 8, 12, 16, 18,20, 24, 28, 32, 36, or the like.

For example, the following may be predefined: WhenDL-DMRS-config-type=1, DL-DMRS-max-len=1, and the quantity of symbolsoccupied by the data block is less than 7, or whenUL-DMRS-config-type=1, UL-DMRS-max-len=1, and the quantity of symbols ofthe data block is less than 7, the DMRS RE overhead value is 6.

For example, the following may be predefined: WhenDL-DMRS-config-type=1, DL-DMRS-max-len=2, and the quantity of symbolsoccupied by the data block is less than 7, or whenUL-DMRS-config-type=1, UL-DMRS-max-len=2, and the quantity of symbolsoccupied by the data block is less than 7, the DMRS RE overhead value is12.

For example, the following may be predefined: WhenDL-DMRS-config-type=2, DL-DMRS-max-len=1, and the quantity of symbolsoccupied by the data block is less than 7, or whenUL-DMRS-config-type=2, UL-DMRS-max-len=1, and the quantity of symbolsoccupied by the data block is less than 7, the DMRS RE overhead value is4.

For example, the following may be predefined: WhenDL-DMRS-config-type=2, DL-DMRS-max-len=2, and the quantity of symbolsoccupied by the data block is less than 7, or whenUL-DMRS-config-type=2, UL-DMRS-max-len=2, and the quantity of symbolsoccupied by the data block is less than 7, the DMRS RE overhead value is8.

For example, the following may be predefined: WhenDL-DMRS-config-type=1, DL-DMRS-max-len=1, and the quantity of symbolsoccupied by the data block is greater than or equal to 7, or whenUL-DMRS-config-type=1, UL-DMRS-max-len=1, and the quantity of symbolsoccupied by the data block is greater than or equal to 7, the DMRS REoverhead value is 12.

For example, the following may be predefined: WhenDL-DMRS-config-type=1, DL-DMRS-max-len=2, and the quantity of symbolsoccupied by the data block is greater than or equal to 7, or whenUL-DMRS-config-type=1, UL-DMRS-max-len=2, and the quantity of symbolsoccupied by the data block is greater than or equal to 7, the DMRS REoverhead value is 24.

For example, the following may be predefined: WhenDL-DMRS-config-type=2, DL-DMRS-max-len=1, and the quantity of symbolsoccupied by the data block is greater than or equal to 7, or whenUL-DMRS-config-type=2, UL-DMRS-max-len=1, and the quantity of symbolsoccupied by the data block is greater than or equal to 7, the DMRS REoverhead value is 8.

For example, the following may be predefined: WhenDL-DMRS-config-type=2, DL-DMRS-max-len=2, and the quantity of symbolsoccupied by the data block is greater than or equal to 7, or whenUL-DMRS-config-type=2, UL-DMRS-max-len=2, and the quantity of symbolsoccupied by the data block is greater than or equal to 7, the DMRS REoverhead value is 16.

In a possible design manner, the first information may include theconfiguration type of the DMRS, the quantity of symbols occupied by theDMRS, the quantity of symbols occupied by the data block, and a positionof a symbol occupied by an additional DMRS. To be specific, acorrespondence between the configuration type of the DMRS, the quantityof symbols occupied by the DMRS, the quantity of symbols occupied by thedata block, and the position of the symbol occupied by the additionalDMRS, and a DMRS RE overhead value may be predefined. The DMRS is a DMRSused when the data block is received.

For example, the following may be predefined: WhenDL-DMRS-config-type=1, DL-DMRS-max-len=1, DL-DMRS-add-pos=2, and thequantity of symbols occupied by the data block is greater than or equalto 7, or when UL-DMRS-config-type=1, UL-DMRS-max-len=1,UL-DMRS-add-pos=2, and the quantity of symbols occupied by the datablock is greater than or equal to 7, the DMRS RE overhead value is 18.

For example, the following may be predefined: WhenDL-DMRS-config-type=1, DL-DMRS-max-len=2, DL-DMRS-add-pos=2, and thequantity of symbols occupied by the data block is greater than or equalto 7, or when UL-DMRS-config-type=1, UL-DMRS-max-len=2,UL-DMRS-add-pos=2, and the quantity of symbols occupied by the datablock is greater than or equal to 7, the DMRS RE overhead value is 36.

For example, the following may be predefined: WhenDL-DMRS-config-type=2, DL-DMRS-max-len=1, DL-DMRS-add-pos=2, and thequantity of symbols occupied by the data block is greater than or equalto 7, or when UL-DMRS-config-type=2, UL-DMRS-max-len=1,UL-DMRS-add-pos=2, and the quantity of symbols occupied by the datablock is greater than or equal to 7, the DMRS RE overhead value is 12.

For example, the following may be predefined: WhenDL-DMRS-config-type=2, DL-DMRS-max-len=2, DL-DMRS-add-pos=2, and thequantity of symbols occupied by the data block is greater than or equalto 7, or when UL-DMRS-config-type=2, UL-DMRS-max-len=2,UL-DMRS-add-pos=2, and the quantity of symbols occupied by the datablock is greater than or equal to 7, the DMRS RE overhead value is 24.

For example, the following may be predefined: WhenDL-DMRS-config-type=1, DL-DMRS-max-len=1, DL-DMRS-add-pos=3, and thequantity of symbols occupied by the data block is greater than or equalto 7, or when UL-DMRS-config-type=1. UL-DMRS-max-len=1,UL-DMRS-add-pos=3, and the quantity of symbols occupied by the datablock is greater than or equal to 7, the DMRS RE overhead value is 24.

For example, the following may be predefined: WhenDL-DMRS-config-type=1, DL-DMRS-max-len=2, DL-DMRS-add-pos=3, and thequantity of symbols occupied by the data block is greater than or equalto 7, or when UL-DMRS-config-type=1, UL-DMRS-max-len=2,UL-DMRS-add-pos=3, and the quantity of symbols occupied by the datablock is greater than or equal to 7, the DMRS RE overhead value is 48.

For example, the following may be predefined: WhenDL-DMRS-config-type=2, DL-DMRS-max-len=1, DL-DMRS-add-pos=3, and thequantity of symbols occupied by the data block is greater than or equalto 7, or when UL-DMRS-config-type=2, UL-DMRS-max-len=1,UL-DMRS-add-pos=3, and the quantity of symbols occupied by the datablock is greater than or equal to 7, the DMRS RE overhead value is 16.

For example, the following may be predefined: WhenDL-DMRS-config-type=2, DL-DMRS-max-len=2, DL-DMRS-add-pos=3, and thequantity of symbols occupied by the data block is greater than or equalto 7, or when UL-DMRS-config-type=2, UL-DMRS-max-len=2,UL-DMRS-add-pos=3, and the quantity of symbols occupied by the datablock is greater than or equal to 7, the DMRS RE overhead value is 32.

Optionally, at least one of P1 to P8 may have a plurality of values.When at least one of P1 to P8 has a plurality of values, the basestation no may inform, via signaling, the UE 120 which one of theplurality of values is the DMRS RE overhead value.

Optionally, the first information may further include a position of aDMRS in a case of a downlink PDSCH mapping type A (DL-DMRS-typeA-pos).When DL-DMRS-typeA-pos=2, there may be three additional DMRSs in a timeunit used for data block transmission. Therefore, a predefined DMRS REoverhead value may be different from a DMRS RE overhead value specificto a case in which DL-DMRS-typeA-pos is not equal to 2.

DL-DMRS-typeA-pos may be used to indicate the position of the DMRS inthe case of the PDSCH mapping type A. Optionally, the position of theDMRS (a position of the first symbol of the DMRS) may be the thirdsymbol or the fourth symbol. For example, an index may be 2 or 3.

It should be understood that the foregoing predefined correspondencesare merely examples. In actual implementation, a correspondence betweena demodulation reference signal RE overhead value and at least one typeof the following information may be predefined: the DCI format, theconfiguration type of the demodulation reference signal, the quantity ofsymbols occupied by the demodulation reference signal, the waveform, theRNTI scrambling manner of the DCI, the quantity of symbols occupied bythe data block, and the position of the symbol occupied by the datablock. For a specific predefinition manner, refer to the foregoingmanners. Details are not described herein again.

After the demodulation reference signal RE overhead value is predefinedfor the first information in any one of the foregoing manners, the basestation 110 and the UE 120 may configure a correspondence, predefined inthis manner, between the first information and the demodulationreference signal RE overhead value. The correspondence configured on theUE 120 may be directly configured, or may be configured by the UE 120after the UE 120 receives the correspondence from the base station 110.

The base station 110 and the UE 120 configure the correspondence,predefined in any one of the foregoing manners, between the firstinformation and the demodulation reference signal RE overhead value, andafter obtaining the first information, the base station no and the UE120 may obtain, based on the first information and the correspondence,the demodulation reference signal RE overhead value, so as to determinea TBS based on the RE overhead value.

FIG. 6 is a schematic flowchart of a method for determining ademodulation reference signal RE overhead value according to anembodiment of this application. It should be understood that FIG. 6shows steps or operations of the communication method, but these stepsor operations are merely examples. In this embodiment of thisapplication, other operations or variations of the operations in FIG. 6may be further performed. In addition, the steps in FIG. 6 may beperformed in a sequence different from that shown in FIG. 6, and it maybe unnecessary to perform all of the operations in FIG. 6.

The method shown in FIG. 6 is performed by a communications apparatus ina communication process. For example, the communications apparatus maybe a base station 110, or may be UE 120.

S610. Obtain first information, where the first information includes atleast one type of the following information: a downlink controlinformation format, a configuration type of a demodulation referencesignal, a quantity of symbols occupied by the demodulation referencesignal, a waveform, an RNTI scrambling manner of downlink controlinformation, a type of a data channel, a quantity of symbols occupied bya data block, and a position of a symbol occupied by the data block.

Optionally, at least one of the downlink control information format, theconfiguration type of the demodulation reference signal, the quantity ofsymbols occupied by the demodulation reference signal, the waveform, theRNTI scrambling manner of the downlink control information, the type ofthe data channel, the quantity of symbols occupied by the data block,and the position of the symbol occupied by the data block may beobtained by the communications apparatus (for example, the base stationor the UE) based on a communication requirement; and/or may be obtained,according to an indication from a communications apparatus serving as atransmit end, by a communications apparatus serving as a receive end.

Optionally, the base station may inform the terminal of the firstinformation via signaling. The terminal determines the first informationbased on the signaling of the base station. The signaling may be higherlayer signaling, or may be physical layer signaling. Details are notlimited in this application.

Optionally, the terminal or the base station may obtain the firstinformation based on a requirement or pre-stored information of theterminal or the base station. Details are not limited in thisapplication.

Optionally, “obtaining” in this application may be referred to asdetermining, obtaining, gaining, confirming, acquiring, or the like.

For example, the base station no may notify the UE 120 of theconfiguration type of the demodulation reference signal via higher layersignaling.

For example, the UE 120 may perform blind detection on the demodulationreference signal by using various RNTIs, and an RNTI scrambling mannercorresponding to successful demodulation is an RNTI scrambling mannerthat needs to be obtained.

For example, the base station and/or the terminal may obtain the firstinformation based on a characteristic of a data channel for data sendingand/or a characteristic of a data channel for data receiving.

S620. Obtain, based on the first information, a quantity, correspondingto the first information, of REs occupied by the demodulation referencesignal, where there is a correspondence between the first informationand the quantity of resource elements occupied by the demodulationreference signal.

Optionally, the first information is in a one-to-one correspondence withthe quantity of resource elements occupied by the demodulation referencesignal.

Optionally, the quantity, corresponding to the first information, ofresource elements occupied by the demodulation reference signal mayinclude a quantity of resource elements occupied by a reference signalused for channel estimation and/or demodulation performed when a datablock corresponding to the first information is received or sent.

Optionally, “obtaining” in this application may be referred to asdetermining, obtaining, gaining, confirming, acquiring, or the like.

It should be understood that the quantity of REs occupied by thedemodulation reference signal herein may be a quantity of possible REs,used to transmit the demodulation reference signal, in a resourcescheduled by the DCI. In other words, in this embodiment of thisapplication, the quantity of REs occupied by the demodulation referencesignal may be greater than or equal to a quantity of REs, actually usedto transmit the demodulation reference signal, in the resource scheduledby using the DCI.

For example, if the first information includes the DCI format or theRNTI scrambling manner of the DCI, the quantity, corresponding to thefirst information, of resource elements occupied by the demodulationreference signal may include a quantity of resource elements occupied bya demodulation reference signal used for channel estimation and/ordemodulation performed when a data block scheduled by the DCI isreceived; or if the first information includes a quantity of symbolsoccupied by the data block or a position of the symbol occupied by thedata block, the quantity, corresponding to the first information, ofresource elements occupied by the demodulation reference signal mayinclude a quantity of resource elements occupied by a demodulationreference signal used for channel estimation and/or demodulationperformed when the data block is received.

For example, when the first information includes the downlink controlinformation format, and the base station 110 or the UE 120 configures acorrespondence between the downlink control information format and aDMRS RE overhead in the foregoing design manner, the obtaining, by thebase station 110 or the UE 120 based on the first information, aquantity of REs occupied by the DMRS may include: when the downlinkcontrol information format is DCI format 1_0, obtaining that thequantity of REs occupied by the DMRS is 4, or when the downlink controlinformation format is DCI format 0_0, obtaining that the quantity of REsoccupied by the DMRS is 6.

For example, when the first information includes the configuration typeof the DMRS, and the base station 110 or the UE 120 configures acorrespondence between the configuration type of the DMRS and a DMRS REoverhead value in the foregoing design manner, the obtaining, based onthe first information, a quantity of REs occupied by the DMRS mayinclude: when the configuration type of the DMRS is DMRS configurationtype 1, obtaining that the quantity of REs occupied by the DMRS is 6; orwhen the configuration type of the DMRS is DMRS configuration type 2,obtaining that the quantity of REs occupied by the DMRS is 4.

For example, when the first information includes the configuration typeof the DMRS and the quantity of symbols occupied by the DMRS, and thebase station 110 or the UE 120 configures a correspondence between theconfiguration type of the DMRS and the quantity of symbols occupied bythe DMRS, and a DMRS RE overhead in the foregoing design manner, theobtaining, based on the first information, a quantity of REs occupied bythe DMRS includes: when the configuration type of the DMRS is DMRSconfiguration type 1, and the quantity of symbols occupied by the DMRSis 1, obtaining that the quantity of REs occupied by the DMRS is 6; orwhen the configuration type of the DMRS is DMRS configuration type 1,and the quantity of symbols occupied by the DMRS is 2, obtaining thatthe quantity of REs occupied by the DMRS is 12; or when theconfiguration type of the DMRS is DMRS configuration type 2, and thequantity of symbols occupied by the DMRS is 1, obtaining that thequantity of REs occupied by the DMRS is 4; or when the configurationtype of the DMRS is DMRS configuration type 2, and the quantity ofsymbols occupied by the DMRS is 2, obtaining that the quantity of REsoccupied by the DMRS is 8.

It should be understood that when the base station no and the UE 120configure, in any one of the foregoing manners, a correspondence betweenthe first information and a DMRS RE overhead value, methods used by thebase station no and the UE 120 to obtain the DMRS RE overhead value aresimilar to those in the foregoing examples. Details are not describedherein again.

According to the method provided in this application, the UE 120 canobtain the DMRS RE overhead value without receiving information sent bythe base station 110 for indicating a CDM group, and can furtherdetermine a TBS based on the RE overhead value.

For example, when receiving fallback DCI from the base station no, theUE 120 can also obtain the DMRS RE overhead value and determine a TBS,thereby improving transmission performance.

In another embodiment of this application, the base station no maynotify, by using signaling, the UE 120 of the DMRS RE overhead value.The signaling may be higher layer signaling, physical layer signaling,or the like.

For example, the base station no sends signaling to the UE 120, and thesignaling is used to indicate that the DMRS RE overhead value is one of4, 6, 8, 12, 24, and the like.

In another embodiment of this application, the base station no mayconfigure, for the UE 120 via higher layer signaling, a plurality ofDMRS RE overhead values, and then the base station no notifies, viasignaling, the UE 120 of a specific value in the plurality of DMRS REoverhead values, so that the UE 120 can determine a TBS.

FIG. 7 is a schematic structural diagram of a communications apparatusaccording to an embodiment of this application. It should be understoodthat the communications apparatus 700 shown in FIG. 7 is merely anexample. The communications apparatus in this embodiment of thisapplication may further include other modules or units, or includemodules having functions similar to those of modules in FIG. 7, or doesnot necessarily need to include all modules in FIG. 7.

The communications apparatus 700 may include a first processing module710 and a second processing module 720. The communications apparatus 700may be configured to perform the method shown in FIG. 6.

For example, the first processing module 710 is configured to obtainfirst information, where the first information includes at least onetype of the following information: a downlink control informationformat, a configuration type of a demodulation reference signal, aquantity of symbols occupied by the demodulation reference signal, awaveform, a radio network temporary identifier scrambling manner ofdownlink control information, a type of a data channel, a quantity ofsymbols occupied by a data block, and a position of a symbol occupied bythe data block.

The second processing module 720 is configured to obtain, based on thefirst information, a quantity, corresponding to the first information,of resource elements occupied by the demodulation reference signal,where there is a correspondence between the first information and thequantity of resource elements occupied by the demodulation referencesignal.

Optionally, the first information is in a one-to-one correspondence withthe quantity of resource elements occupied by the demodulation referencesignal.

Optionally, when the first information includes the downlink controlinformation format, the second processing module 720 is specificallyconfigured to:

if the downlink control information format is downlink controlinformation format 1_0, obtain that the quantity of resource elementsoccupied by the demodulation reference signal is 4 or 6; and/or

if the downlink control information format is downlink controlinformation format 0_0, obtain that the quantity of resource elementsoccupied by the demodulation reference signal is 6 or 4.

Optionally, when the first information includes the configuration typeof the demodulation reference signal, the second processing module 720is specifically configured to:

if the configuration type of the demodulation reference signal isconfiguration type 1, obtain that the quantity of resource elementsoccupied by the demodulation reference signal is 6; and/or

if the configuration type of the demodulation reference signal isconfiguration type 2, obtain that the quantity of resource elementsoccupied by the demodulation reference signal is 4.

Optionally, when the first information includes the configuration typeof the demodulation reference signal and the quantity of symbolsoccupied by the demodulation reference signal, the second processingmodule 720 is specifically configured to:

if the configuration type of the demodulation reference signal isconfiguration type 1, and the quantity of symbols occupied by thedemodulation reference signal is 1, obtain that the quantity of resourceelements occupied by the demodulation reference signal is 6; and/or

if the configuration type of the demodulation reference signal isconfiguration type 1, and the quantity of symbols occupied by thedemodulation reference signal is 2, obtain that the quantity of resourceelements occupied by the demodulation reference signal is 12; and/or

if the configuration type of the demodulation reference signal isconfiguration type 2, and the quantity of symbols occupied by thedemodulation reference signal is 1, obtain that the quantity of resourceelements occupied by the demodulation reference signal is 4; and/or

if the configuration type of the demodulation reference signal isconfiguration type 2, and the quantity of symbols occupied by thedemodulation reference signal is 2, obtain that the quantity of resourceelements occupied by the demodulation reference signal is 8.

Optionally, the second processing module 720 is specifically configuredto obtain the quantity of resource elements occupied by the demodulationreference signal, based on the correspondence between the firstinformation and the quantity of resource elements occupied by thedemodulation reference signal.

FIG. 8 is a schematic structural diagram of a communications deviceaccording to an embodiment of this application. It should be understoodthat the communications device 800 shown in FIG. 8 is merely an example.The communications device in this embodiment of this application mayfurther include other modules or units, or include modules havingfunctions similar to those of modules in FIG. 8, or does not necessarilyneed to include all modules in FIG. 8.

The communications device 800 includes at least one processor 810 and acommunications interface 820. The communications device 800 may beconfigured to perform the method shown in FIG. 6.

For example, the communications interface is configured to exchangeinformation with another communications device, and the at least oneprocessor 810 executes one or more instructions, so that thecommunications device 800 performs the method shown in FIG. 6.

Optionally, the communications device 800 may be an access networkdevice or a terminal device. When the communications device 800 is aterminal device, the correspondence may be configured by the terminaldevice according to a communication protocol, or may be received by theterminal device from an access network device.

FIG. 9 is a schematic structural diagram of a system chip according toan embodiment of this application. It should be understood that thesystem chip 900 shown in FIG. 9 is merely an example. The system chip inthis embodiment of this application may further include other modules orunits, or include modules having functions similar to those of modulesin FIG. 9, or does not necessarily need to include all modules in FIG.9.

The system chip 900 includes at least one processor 910 and aninput/output interface 920. The system chip 900 may be configured toperform the method shown in FIG. 6.

For example, the input/output interface is configured to exchangeinformation with another communications device, and the at least oneprocessor 910 executes one or more instructions, so that the system chip900 performs the method shown in FIG. 6.

FIG. 10 is a schematic structural diagram of a communications systemaccording to an embodiment of this application. It should be understoodthat the communications system 1000 shown in FIG. 10 is merely anexample. The communications system in this embodiment of thisapplication may further include other modules or units, or includemodules having functions similar to those of modules in FIG. 10, or doesnot necessarily need to include all modules in FIG. 10.

The communications system 1000 includes a communications device 1010.The communications device 1010 may be the communications device 800shown in FIG. 8.

A person of ordinary skill in the art may be aware that units andalgorithm steps in the examples described with reference to theembodiments disclosed in this specification can be implemented byelectronic hardware or a combination of computer software and electronichardware. Whether the functions are performed by hardware or softwaredepends on particular applications and design constraints of thetechnical solutions. A person skilled in the art may use differentmethods to implement the described functions for all particularapplications, but it should not be considered that the implementationgoes beyond the scope of this application.

It may be clearly understood by a person skilled in the art that, forthe purpose of convenient and brief description, for a specific workingprocess of the foregoing system, apparatus, and unit, refer to acorresponding process in the foregoing method embodiments. Details arenot described herein again.

This application further provides the following embodiments. It shouldbe noted that the following embodiments are numbered in a way differentfrom a manner in which the foregoing embodiments in this application arenumbered.

Embodiment 1: A method for obtaining a quantity of resource elements ina communication process is provided, and the method includes:

obtaining first information, where the first information includes atleast one type of the following information: a downlink controlinformation format, a configuration type of a demodulation referencesignal, a quantity of symbols occupied by the demodulation referencesignal, a waveform, a radio network temporary identifier scramblingmanner of downlink control information, a type of a data channel, aquantity of symbols occupied by a data block, and a position of a symboloccupied by the data block; and obtaining, based on the firstinformation, a quantity, corresponding to the first information, ofresource elements occupied by the demodulation reference signal, wherethere is a correspondence between the first information and the quantityof resource elements occupied by the demodulation reference signal.

Embodiment 2: According to the method in Embodiment 1, the firstinformation is in a one-to-one correspondence with the quantity ofresource elements occupied by the demodulation reference signal.

Embodiment 3: According to the method in Embodiment 1 or 2, when thefirst information includes the downlink control information format, theobtaining, based on the first information, a quantity of resourceelements occupied by the demodulation reference signal includes:

if the downlink control information format is downlink controlinformation format 1_0, obtaining that the quantity of resource elementsoccupied by the demodulation reference signal is 4 or 6; and/or if thedownlink control information format is downlink control informationformat 0_0, obtaining that the quantity of resource elements occupied bythe demodulation reference signal is 6 or 4.

Embodiment 4: According to the method in Embodiment 1 or 2, when thefirst information includes the configuration type of the demodulationreference signal, the obtaining, based on the first information, aquantity of resource elements occupied by the demodulation referencesignal includes:

if the configuration type of the demodulation reference signal isconfiguration type 1, obtaining that the quantity of resource elementsoccupied by the demodulation reference signal is 6; and/or if theconfiguration type of the demodulation reference signal is configurationtype 2, obtaining that the quantity of resource elements occupied by thedemodulation reference signal is 4.

Embodiment 5: According to the method in Embodiment 1 or 2, the firstinformation includes the configuration type of the demodulationreference signal and the quantity of symbols occupied by thedemodulation reference signal, the obtaining, based on the firstinformation, a quantity of resource elements occupied by thedemodulation reference signal includes: if the configuration type of thedemodulation reference signal is configuration type 1, and the quantityof symbols occupied by the demodulation reference signal is 1, obtainingthat the quantity of resource elements occupied by the demodulationreference signal is 6; and/or if the configuration type of thedemodulation reference signal is configuration type 1, and the quantityof symbols occupied by the demodulation reference signal is 2, obtainingthat the quantity of resource elements occupied by the demodulationreference signal is 12; and/or if the configuration type of thedemodulation reference signal is configuration type 2, and the quantityof symbols occupied by the demodulation reference signal is 1, obtainingthat the quantity of resource elements occupied by the demodulationreference signal is 4; and/or if the configuration type of thedemodulation reference signal is a configuration type 2, and thequantity of symbols occupied by the demodulation reference signal is 2,obtaining that the quantity of resource elements occupied by thedemodulation reference signal is 8.

Embodiment 6: According to the method in any one of Embodiment 1 toEmbodiment 5, the obtaining, based on the first information, a quantityof resource elements occupied by the demodulation reference signalincludes: obtaining the quantity of resource elements occupied by thedemodulation reference signal, based on the correspondence between thefirst information and the quantity of resource elements occupied by thedemodulation reference signal.

Embodiment 7: According to the method in Embodiment 6, the method isperformed by a terminal device, and the correspondence is configured bythe terminal device according to a communication protocol or received bythe terminal device from an access network device.

Embodiment 8: A communications apparatus is provided and includes: afirst processing module, configured to obtain first information, wherethe first information includes at least one type of the followinginformation: a downlink control information format, a configuration typeof a demodulation reference signal, a quantity of symbols occupied bythe demodulation reference signal, a waveform, a radio network temporaryidentifier scrambling manner of downlink control information, a type ofa data channel, a quantity of symbols occupied by a data block, and aposition of a symbol occupied by the data block; and a second processingmodule, configured to obtain, based on the first information, aquantity, corresponding to the first information, of resource elementsoccupied by the demodulation reference signal, where there is acorrespondence between the first information and the quantity ofresource elements occupied by the demodulation reference signal.

Embodiment 9: According to the communications apparatus in Embodiment 8,the first information is in a one-to-one correspondence with thequantity of resource elements occupied by the demodulation referencesignal.

Embodiment 10: According to the communications apparatus in Embodiment 8or 9, when the first information includes the downlink controlinformation format, the second processing module is specificallyconfigured to: if the downlink control information format is downlinkcontrol information format 1_0, obtain that the quantity of resourceelements occupied by the demodulation reference signal is 4 or 6; and/orif the downlink control information format is downlink controlinformation format 0_0, obtain that the quantity of resource elementsoccupied by the demodulation reference signal is 6 or 4.

Embodiment 11: According to the communications apparatus in Embodiment 8or 9, when the first information includes the configuration type of thedemodulation reference signal, the second processing module isspecifically configured to: if the configuration type of thedemodulation reference signal is configuration type 1, obtain that thequantity of resource elements occupied by the demodulation referencesignal is 6; and/or if the configuration type of the demodulationreference signal is configuration type 2, obtain that the quantity ofresource elements occupied by the demodulation reference signal is 4.

Embodiment 12: According to the communications apparatus in Embodiment 8or 9, when the first information includes the configuration type of thedemodulation reference signal and the quantity of symbols occupied bythe demodulation reference signal, the second processing module isspecifically configured to: if the configuration type of thedemodulation reference signal is configuration type 1, and the quantityof symbols occupied by the demodulation reference signal is 1, obtainthat the quantity of resource elements occupied by the demodulationreference signal is 6; and/or if the configuration type of thedemodulation reference signal is configuration type 1, and the quantityof symbols occupied by the demodulation reference signal is 2, obtainthat the quantity of resource elements occupied by the demodulationreference signal is 12; and/or if the configuration type of thedemodulation reference signal is configuration type 2, and the quantityof symbols occupied by the demodulation reference signal is 1, obtainthat the quantity of resource elements occupied by the demodulationreference signal is 4; and/or if the configuration type of thedemodulation reference signal is configuration type 2, and the quantityof symbols occupied by the demodulation reference signal is 2, obtainthat the quantity of resource elements occupied by the demodulationreference signal is 8.

Embodiment 13: According to the communications apparatus in any one ofembodiments 8 to 12, the second processing module is specificallyconfigured to obtain the quantity of resource elements occupied by thedemodulation reference signal, based on the first information and thecorrespondence between the first information and the quantity ofresource elements occupied by the demodulation reference signal.

Embodiment 14: According to the communications apparatus in Embodiment13, the communications apparatus is a terminal device, and thecorrespondence is configured by the terminal device according to acommunication protocol or received by the terminal device from an accessnetwork device.

Embodiment 15: A communications device is provided, and thecommunications device includes at least one processor and acommunications interface. The communications interface is used by thecommunications device to exchange information with anothercommunications device, and when one or more instructions is executed bythe at least one processor, the communications device performs themethod in any one of Embodiments 1 to 7.

Embodiment 16: A computer program storage medium is provided. Thecomputer program storage medium has one or more instructions, and whenthe program instruction is directly or indirectly executed, functions ofeither of the following devices in the method in any one of Embodiments1 to 7 are performed: the terminal device and the access network device.

Embodiment 17: A chip system is provided. The chip system includes atleast one processor, and when one or more instructions is executed bythe at least one processor, functions of either of the following devicesin the method in any one of Embodiments 1 to 7 are performed: theterminal device and the access network device.

Embodiment 18: A communications system is provided, and thecommunications system includes the communications device in Embodiment15.

In the several embodiments provided in this application, it should beunderstood that the disclosed system, apparatus, and method may beimplemented in other manners. For example, the described apparatusembodiments are merely examples. For example, the unit division ismerely logical function division and there may be another divisionmanner during actual implementation. For example, a plurality of unitsor components may be combined or integrated into another system, or somefeatures may be ignored or may not be performed. In addition, thedisplayed or discussed mutual couplings or direct couplings orcommunication connections may be implemented via some interfaces. Theindirect couplings or communication connections between the apparatusesor units may be implemented in electrical, mechanical, or other forms.

The units described as separate parts may or may not be physicallyseparate. Parts displayed as units may or may not be physical units, andmay be located in one position, or may be distributed onto a pluralityof network units. Some or all of the units may be selected based onactual requirements to achieve the objectives of the solutions of theembodiments.

In addition, functional units in the embodiments of this application maybe integrated into one processing unit, or each of the units may existalone physically, or two or more units may be integrated into one unit.

When the functions are implemented in a form of a software functionalunit and sold or used as an independent product, the functions may bestored in a computer readable storage medium. Based on such anunderstanding, the technical solutions of this application essentially,or the part contributing to the prior art, or some of the technicalsolutions may be implemented in a form of a software product. Thecomputer software product is stored in a storage medium, and includesseveral instructions for instructing a computer device (which may be apersonal computer, a server, a network device, or the like) to performall or some of the steps of the methods described in the embodiments ofthis application. The storage medium includes any medium that can storeprogram code, such as a USB flash drive, a removable hard disk, aread-only memory (read-only memory, ROM), a random access memory (randomaccess memory, RAM), a magnetic disk, or a compact disc.

The foregoing descriptions are merely specific implementations of thisapplication, but are not intended to limit the protection scope of thisapplication. Any variation or replacement readily figured out by aperson skilled in the art within the technical scope disclosed in thisapplication shall fall within the protection scope of this application.Therefore, the protection scope of this application shall be subject tothe protection scope of the claims.

What is claimed is:
 1. A method comprising: determining a downlinkcontrol information format of downlink control information, the downlinkcontrol information scheduling a data transmission; determining, basedon the downlink control information format, a quantity of resourceelements per physical resource block (PRS) carrying a demodulationreference signal (DMRS) of the data transmission; and determining atransport block size (TBS) used for the data transmission based on thequantity of resource elements determined.
 2. The method according toclaim 1, wherein the downlink control information format is DCI format0_0 or DCI format 1_0, and the quantity of resource elements is 6, 12,or
 24. 3. The method according to claim 1, wherein the method furthercomprises: obtaining a configuration type of the DMRS and a quantity ofsymbols occupied by the DMRS; and wherein determining the quantity ofresource elements comprises determining the quantity of resourceelements based on the downlink control information format, theconfiguration type of the DMRS and the quantity of symbols occupied bythe DMRS, and wherein the downlink control information format is DCIformat 0_0 or DCI format 1_0, the configuration type of the DMRS is DMRSconfiguration type 1, the quantity of symbols occupied by the DMRS is 1,and the quantity of resource elements is 6, 12, or
 24. 4. The methodaccording to claim 1, wherein the method further comprises: obtaining aconfiguration type of the DMRS, a quantity of symbols occupied by theDMRS, and a quantity of symbols occupied by a transport block of thedata transmission; and wherein determining the quantity of resourceelements comprises determining the quantity of resource elements basedon the downlink control information format, the configuration type ofthe DMRS, the quantity of symbols occupied by the DMRS, and the quantityof symbols occupied by the transport block; and wherein: the downlinkcontrol information format is DCI format 0_0 or DCI format 1_0, theconfiguration type of the DMRS is DMRS configuration type 1, thequantity of symbols occupied by the DMRS is 1, the quantity of symbolsoccupied by the transport block is greater than or equal to 7, and thequantity of resource elements is 12, 24, or 36; or the downlink controlinformation format is DCI format 0_0 or DCI format 1_0, theconfiguration type of the DMRS is DMRS configuration type 1, thequantity of symbols occupied by the DMRS is 1, the quantity of symbolsoccupied by the transport block is less than 7, and the quantity ofresource elements is 6, 12, or
 24. 5. The method according to claim 1,wherein the method further comprises: obtaining a configuration type ofthe DMRS, a quantity of symbols occupied by the DMRS, a quantity ofsymbols occupied by a transport block of the data transmission, and aposition of a symbol occupied by the transport block; and whereindetermining the quantity of resource elements comprises determining thequantity of resource elements based on the downlink control informationformat, the configuration type of the DMRS, the quantity of symbolsoccupied by the DMRS, the quantity of symbols occupied by the transportblock, and the position of the symbol occupied by the transport block;and wherein: the downlink control information format is DCI format 0_0or DCI format 1_0, the configuration type of the DMRS is DMRSconfiguration type 1, the quantity of symbols occupied by the DMRS is 1,the quantity of symbols occupied by the transport block is greater thanor equal to 7, and the quantity of resource elements is 12, 24, or 36;or the downlink control information format is DCI format 0_0 or DCIformat 1_0, the configuration type of the DMRS is DMRS configurationtype 1, the quantity of symbols occupied by the DMRS is 1, the quantityof symbols occupied by the transport block is less than 7, and thequantity of resource elements is 6, 12, or
 24. 6. The method accordingto claim 1, wherein the method further comprises: obtaining aconfiguration type of the DMRS, a quantity of symbols occupied by theDMRS, a quantity of symbols occupied by a transport block of the datatransmission, and a quantity of additional DMRSs in the DMRS; andwherein determining the quantity of resource elements comprisesdetermining the quantity of resource elements based on the downlinkcontrol information format, the configuration type of the DMRS, thequantity of symbols occupied by the DMRS, the quantity of symbolsoccupied by the transport block, and the quantity of the additionalDMRSs, and wherein the downlink control information format is DCI format0_0 or DCI format 1_0, the configuration type of the DMRS is DMRSconfiguration type 1, the quantity of symbols occupied by the DMRS is 1,and the quantity of the additional DMRSs is 0, 1, or
 2. 7. The methodaccording to claim 1, wherein the method further comprises; obtaining aconfiguration type of the DMRS, a quantity of symbols occupied by theDMRS, a quantity of symbols occupied by a transport block of the datatransmission, a position of a symbol occupied by the transport block,and a quantity of additional DMRSs in the DMRS; and wherein determiningthe quantity of resource elements comprises determining the quantity ofresource elements based on the downlink control information format, theconfiguration type of the DMRS, the quantity of symbols occupied by theDMRS, the quantity of symbols occupied by the transport block, theposition of the symbol occupied by the transport block, and the quantityof the additional DMRSs, and wherein the downlink control informationformat is DCI format 0_0 or DCI format 1_0, the configuration type ofthe DMRS is DMRS configuration type 1, the quantity of symbols occupiedby the DMRS is 1, and the quantity of the additional DMRSs is 0, 1, or2.
 8. The method according to claim 1, wherein the quantity of resourceelements has a correspondence with the downlink control informationformat.
 9. The method according to claim 8, wherein determining thequantity of resource elements comprises: determining the quantity ofresource elements based on the correspondence between the downlinkcontrol information format and the quantity of resource elements. 10.The method according to claim 1, wherein the method is performed by aterminal device in a wireless mobile communications system, or performedby a chip in the terminal device.
 11. An apparatus comprising: at leastone processor, configured to: determine a downlink control informationformat of downlink control information, the downlink control informationscheduling a data transmission; determine, based on the downlink controlinformation format, a quantity of resource elements per physicalresource block carrying a demodulation reference signal (DMRS) of thedata transmission; and determine a transport block size (TBS) used forthe data transmission based on the quantity of resource elementsdetermined.
 12. The apparatus according to claim 11, wherein thedownlink control information format is DCI format 0_0 or DCI format 1_0,and the quantity of resource elements is 6, 12, or
 24. 13. The apparatusaccording to claim 11, wherein the at least one processor is furtherconfigured to obtain a configuration type of the DMRS and a quantity ofsymbols occupied by the DMRS, wherein determining the quantity ofresource elements comprises determining the quantity of resourceelements based on the downlink control information format, theconfiguration type of the DMRS and the quantity of symbols occupied bythe DMRS, and wherein the downlink control information format is DCIformat 0_0 or DCI format 1_0, the configuration type of the DMRS is DMRSconfiguration type 1, the quantity of symbols occupied by the DMRS is 1,and the quantity of resource elements is 6, 12, or
 24. 14. The apparatusaccording to claim 11, wherein the at least one processor is furtherconfigured to obtain a configuration type of the DMRS, a quantity ofsymbols occupied by the DMRS, and a quantity of symbols occupied by atransport block of the data transmission; and wherein determining thequantity of resource elements comprises determining the quantity ofresource elements based on the downlink control information format, theconfiguration type of the DMRS, the quantity of symbols occupied by theDMRS, and the quantity of symbols occupied by the transport block; andwherein: the downlink control information format is DCI format 0_0 orDCI format 1_0, the configuration type of the DMRS is DMRS configurationtype 1, the quantity of symbols occupied by the DMRS is 1, the quantityof symbols occupied by the transport block is greater than or equal to7, and the quantity of resource elements is 12, 24, or 36; or thedownlink control information format is DCI format 0_0 or DCI format 1_0,the configuration type of the DMRS is DMRS configuration type 1, thequantity of symbols occupied by the DMRS is obtained as 1, the quantityof symbols occupied by the transport block is less than 7, and thequantity of resource elements is 6, 12, or
 24. 15. The apparatusaccording to claim 11, wherein the at least one processor is furtherconfigured to obtain a configuration type of the DMRS, a quantity ofsymbols occupied by the DMRS, a quantity of symbols occupied by atransport block of the data transmission, and a position of a symboloccupied by the transport block; and wherein determining the quantity ofresource elements comprises determining the quantity of resourceelements based on the downlink control information format, theconfiguration type of the DMRS, the quantity of symbols occupied by theDMRS, the quantity of symbols occupied by the transport block, and theposition of the symbol occupied by the transport block; and wherein: thedownlink control information format is DCI format 0_0 or DCI format 1_0,the configuration type of the DMRS is DMRS configuration type 1, thequantity of symbols occupied by the DMRS is 1, the quantity of symbolsoccupied by the transport block is greater than or equal to 7, and thequantity of resource elements is 12, 24, or 36; or the downlink controlinformation format is DCI format 0_0 or DCI format 1_0, theconfiguration type of the DMRS is DMRS configuration type 1, thequantity of symbols occupied by the DMRS is 1, the quantity of symbolsoccupied by the transport block is less than 7, and the quantity ofresource elements is 6, 12, or
 24. 16. The apparatus according to claim11, wherein the at least one processor is further configured to obtain aconfiguration type of the DMRS, a quantity of symbols occupied by theDMRS, a quantity of symbols occupied by a transport block of the datatransmission, and a quantity of additional DMRSs in the DMRS; andwherein determining the quantity of resource elements comprisesdetermining the quantity of resource elements based on the downlinkcontrol information format, the configuration type of the DMRS, thequantity of symbols occupied by the DMRS, the quantity of symbolsoccupied by the transport block, and the quantity of the additionalDMRSs, and wherein the downlink control information format is DCI format0_0 or DCI format 1_0, the configuration type of the DMRS is DMRSconfiguration type 1, the quantity of symbols occupied by the DMRS is 1,and the quantity of the additional DMRSs is 0, 1, or
 2. 17. Theapparatus according to claim ii, wherein the at least one processor isfurther configured to obtain a configuration type of the DMRS, aquantity of symbols occupied by the DMRS, a quantity of symbols occupiedby a transport block of the data transmission, a position of a symboloccupied by the transport block, and a quantity of additional DMRSs; andwherein determining the quantity of resource elements comprisesdetermining the quantity of resource elements based on the downlinkcontrol information format, the configuration type of the DMRS, thequantity of symbols occupied by the DMRS, the quantity of symbolsoccupied by the transport block, the position of the symbol occupied bythe transport block, and the quantity of the additional DMRSs, andwherein the downlink control information format is DCI format 0_0 or DCIformat 1_0, the configuration type of the DMRS is DMRS configurationtype 1, the quantity of symbols occupied by the DMRS is 1, and thequantity of the additional DMRSs is 0, 1, or
 2. 18. The apparatusaccording to claim 11, wherein the quantity of resource elements has acorrespondence with the downlink control information format.
 19. Theapparatus according to claim 18, wherein the at least one processor isconfigured to determine the quantity of resource elements based on thecorrespondence between the downlink control information format and thequantity of resource elements.
 20. The apparatus according to claim 11,wherein the apparatus is a terminal device in a wireless mobilecommunications system or a chip in the terminal device.
 21. Anon-transitory computer-readable media storing computer instructions,that when executed by one or more processors, cause the one or moreprocessors to perform steps of: determining a downlink controlinformation format of downlink control information, the downlink controlinformation scheduling a data transmission determining, based on thedownlink control information format, a quantity of resource elements perphysical resource block carrying a demodulation reference signal (DMRS)of the data transmission; and determining a transport block size (TBS)used for the data transmission based on the quantity of resourceelements determined.
 22. The non-transitory computer-readable mediaaccording to claim 21, wherein the downlink control information formatis DCI format 0_0 or DCI format 1_0, and the quantity of resourceelements is 6, 12, or
 24. 23. The non-transitory computer-readable mediaaccording to claim 21, wherein the steps further comprise: obtaining aconfiguration type of the DMRS and a quantity of symbols occupied by theDMRS; and wherein determining the quantity of resource elementscomprises determining the quantity of resource elements based on thedownlink control information format, the configuration type of the DMRSand the quantity of symbols occupied by the DMRS, and wherein thedownlink control information format is DCI format 0_0 or DCI format 1_0,the configuration type of the DMRS is DMRS configuration type 1, thequantity of symbols occupied by the DMRS is 1, and the quantity ofresource elements is 6, 12, or
 24. 24. The non-transitorycomputer-readable media according to claim 21, wherein the steps furthercomprise: obtaining a configuration type of the DMRS, a quantity ofsymbols occupied by the DMRS, and a quantity of symbols occupied by atransport block of the data transmission; wherein determining thequantity of resource elements comprises determining the quantity ofresource elements based on the downlink control information format, theconfiguration type of the DMRS, the quantity of symbols occupied by theDMRS, and the quantity of symbols occupied by the transport block; andwherein: the downlink control information format is DCI format 0_0 orDCI format 1_0, the configuration type of the DMRS is DMRS configurationtype 1, the quantity of symbols occupied by the DMRS is 1, the quantityof symbols occupied by the transport block is greater than or equal to7, and the quantity of resource elements is 12, 24, or 36; or thedownlink control information format is DCI format 0_0 or DCI format 1_0,the configuration type of the DMRS is DMRS configuration type 1, thequantity of symbols occupied by the DMRS is 1, the quantity of symbolsoccupied by the transport block is less than 7, and the quantity ofresource elements is 6, 12, or
 24. 25. The non-transitorycomputer-readable media according to claim 21, wherein the steps furthercomprise: obtaining a configuration type of the DMRS, a quantity ofsymbols occupied by the DMRS, a quantity of symbols occupied by atransport block of the data transmission, and a position of a symboloccupied by the transport block; and wherein determining the quantity ofresource elements comprises determining the quantity of resourceelements based on the downlink control information format, theconfiguration type of the DMRS, the quantity of symbols occupied by theDMRS, the quantity of symbols occupied by the transport block, and theposition of the symbol occupied by the transport block; and wherein: thedownlink control information format is DCI format 0_0 or DCI format 1_0,the configuration type of the DMRS is DMRS configuration type 1, thequantity of symbols occupied by the DMRS is 1, the quantity of symbolsoccupied by the transport block is greater than or equal to 7, and thequantity of resource elements is 12, 24, or 36; or the downlink controlinformation format is DCI format 0_0 or DCI format 1_0, theconfiguration type of the DMRS is DMRS configuration type 1, thequantity of symbols occupied by the DMRS is 1, the quantity of symbolsoccupied by the transport block is less than 7, and the quantity ofresource elements is 6, 12, or
 24. 26. The non-transitorycomputer-readable media according to claim 21, wherein the steps furthercomprise: obtaining a configuration type of the DMRS, a quantity ofsymbols occupied by the DMRS, a quantity of symbols occupied by atransport block of the data transmission, and a quantity of additionalDMRSs in the DMRS; and wherein determining the quantity of resourceelements comprises determining the quantity of resource elements basedon the downlink control information format, the configuration type ofthe DMRS, the quantity of symbols occupied by the DMRS, the quantity ofsymbols occupied by the transport block, and the quantity of theadditional DMRSs, and wherein the downlink control information format isDCI format 0_0 or DCI format 1_0, the configuration type of the DMRS isDMRS configuration type 1, the quantity of symbols occupied by the DMRSis 1, and the quantity of the additional DMRSs is 0, 1, or
 2. 27. Thenon-transitory computer-readable media according to claim 21, whereinthe steps further comprise: obtaining a configuration type of the DMRS,a quantity of symbols occupied by the DMRS, a quantity of symbolsoccupied by a transport block of the data transmission, a position of asymbol occupied by the transport block, and a quantity of additionalDMRSs in the DMRS; and wherein determining the quantity of resourceelements comprises determining the quantity of resource elements basedon the downlink control information format, the configuration type ofthe DMRS, the quantity of symbols occupied by the DMRS, the quantity ofsymbols occupied by the transport block, the position of the symboloccupied by the transport block, and the quantity of the additionalDMRSs, and wherein the downlink control information format is DCI format0_0 or DCI format 1_0, the configuration type of the DMRS is DMRSconfiguration type 1, the quantity of symbols occupied by the DMRS is 1,and the quantity of the additional DMRSs is 0, 1, or
 2. 28. Thenon-transitory computer-readable media according to claim 21, whereinthe quantity of resource elements has a correspondence with the downlinkcontrol information format.
 29. The non-transitory computer-readablemedia according to claim 28, wherein determining the quantity ofresource elements comprises: determining the quantity of resourceelements based on the correspondence between the downlink controlinformation format and the quantity of resource elements.
 30. Thenon-transitory computer-readable media according to claim 21, whereinthe steps are performed by a terminal device in a wireless mobilecommunications system, or performed by a chip in the terminal device.